Four new detections of gravitational waves have been announced at the Gravitational Waves Physics and Astronomy Workshop, at the University of Maryland in the United States.
This brings the total number of detections to 11, since the first back in 2015.
Ten are from binary black hole mergers and one from the merger of two neutron stars, which are the dense remains of stellar explosions. One black hole merger was extraordinarily distant, and the most powerful explosion ever observed in astronomy.
The latest news comes just a month after doubts were raised about the initial detection. In late October an article in New Scientist, headlined Exclusive: Grave doubts over LIGO’s discovery of gravitational waves, raised the idea that it “might have been an illusion”.
So how confident are we that we are detecting gravitational waves, and not seeing an illusion?
Open to scrutiny
All good scientists understand that scrutiny and scepticism is the power of science. All theories and all knowledge are provisional, as science slowly homes in on our best understanding of the truth. There is no certainty, only probability and statistical significance.
Years ago the team searching for gravitational waves with the Laser Interferometer Gravitational-Wave Observatory (LIGO), determined the levels of statistical significance needed to make a claim of detection.
For each signal we determine the false alarm rate. This tells you how many years you would need to wait before you have an even chance of a random signal mimicking your real signal.
The weakest signal detected so far has a false alarm rate of one every five years, so still there is a chance that it could have been accidental.
Other signals are much stronger. For the three strongest signals detected so far you would have to wait from 1,000 times to 10 billion billion times the age of the universe for the signals to occur by chance.
Knowing what to listen out for
The detection of gravitational waves is a bit like acoustic ornithology.
Imagine you study birds and want to determine the population of birds in a forest. You know the calls of the various bird species.
When a bird call matches your predetermined call, you jump with excitement. Its loudness tells you how far away it is. If it was very faint against the background noise, you may be uncertain.
But you need to consider the lyre birds that mimic other species. How do you know that sound of a kookaburra isn’t actually made by a lyre bird? You have to be very rigorous before you can claim there is a kookaburra in the forest. Even then you will only be able to be confident if you make further detections.
In gravitational waves we use memorised sounds called templates. There is one unique sound for the merger of each possible combination of black hole masses and spins. Each template is worked out using Einstein’s theory of gravitational wave emission.
To avoid missing signals or claiming false positives, the utmost rigour is needed to analyse the data. Huge teams look over the data, search for flaws, criticise each other, review computer codes and finally review proposed publications for accuracy. Separate teams use different methods of analysis, and finally compare results.
Next comes reproducibility – the same result recorded again and again. Reproducibility is a critical component of science.
The signals detected
Before LIGO made its first public announcement of gravitational waves, two more signals had been detected, each of them picked up in two detectors. This increased our confidence and told us that there is a population of colliding black holes out there, not just a single event that could be something spurious.
The first detected gravitational wave was astonishingly loud and it matched a pre-determined template. It was so good that LIGO spent many weeks trying to work out if it was possible for it to have been a prank, deliberately injected by a hacker.
While LIGO scientists eventually convinced themselves that the event was real, further discoveries greatly increased our confidence. In August 2017 a signal was detected by the two LIGO detectors and the Virgo detector in Italy.
On August 17 last year a completely different, but long predicted type of signal was observed from a coalescing pair of neutron stars, accompanied by the predicted burst of gamma rays and light.
The black hole mergers
Now the LIGO-Virgo collaboration has completed the analysis of all the data since September 2015.
For each signal we determine the mass of the two colliding black holes, the mass of the new black hole that they create, and rather roughly, the distance and the direction.
Each signal has been seen in two or three detectors almost simultaneously (they were separated by milliseconds).
Eight of the 20 initial black holes have masses between 30 and 40 Suns, six are in the 20s, three are in the teens and only two are as low as 7 to 8 Suns. Only one is near 50, the biggest pre-collision black hole yet seen.
These are the numbers that will help us work out where all these black holes were made, how they were made, and how many are out there. To answer these big questions we need many more signals.
The weakest of the new signals, GW170729, was detected on July 29, 2017. It was the collision of a black hole 50 times the mass of the Sun, with another 34 times the mass of the Sun.
This was by far the most distant event, having taken place, most likely, 5 billion years ago – before the birth of Earth and the Solar system 4.6 billion years ago. Despite the weak signal, it was the most powerful gravitational explosion discovered, so far.
But because the signal was weak, this is the detection with the false alarm rate of one every five years.
LIGO and Virgo are improving their sensitivity year by year, and will be finding many more events.
With planned new detectors we anticipate ten times more sensitivity. Then we expect to be detecting new signals about every five minutes.
Active galaxies are some of the most luminous and impressive objects in the sky. They tend to be massive, distant and emit extraordinary amounts of energy as material falls into the supermassive black hole that lurks at their centre. Astronomers have recently discovered that some of them are also hidden from plain view by huge amounts of gas and smoke-like dust. But it is unclear how these rare objects form and feed.
Now our team of astronomers has worked out more about the origin of the most luminous galaxy found in the universe: a “quasar” called W2246. Our findings, published in Science, show clear signs of W2246 forming by several galaxies merging.
W2246 was first discovered in the all-sky infrared survey made by the WISE spacecraft in 2010. But we don’t see it as it looks today. When we look out into the universe we detect light that has taken some appreciable time to get to us. This galaxy is so far away that we see it as it was when the universe was only about 8% of its present age.
The object is extremely bright – about 10,000 times more luminous than our galaxy, the Milky Way. Previous work using a range of cutting-edge telescopes – including the Atacama Large Millimetre Array (ALMA), and the Hubble and Herschel Space Telescopes – confirmed in 2016 that W2246 is the current holder of the record for the most luminous galaxy in the universe.
The bulk of the power from W2246 emanates from a relatively compact region in its centre, several times smaller than the Milky Way. The images also show that this region contains a remarkable cloud of hot, uniform, high-pressure gas, plausibly starting to expand out as a bubble in all directions.
The latest observations were carried out by my colleague Tanio Diaz Santos in Chile, and 11 other astronomers, using the ALMA and Jansky Very Large Array (JCLA) telescopes, at excellent sites in Chile and New Mexico respectively. The work has revealed the smog of gas and dust contained within W2246 in unprecedented detail.
The fact that W2246 could be so bright without feeding on nearby galaxies has long been a mystery to astronomers – potentially challenging our theories about galaxy formation. But our new results reveal that there are indeed a number of nearby companion galaxies that are in the process of being gobbled up by this object. This is evidenced by connecting dust bridges of carbon-rich solid material, similar to diesel soot. These trace the routes along which matter from the companion galaxies is being sucked in towards the supermassive black hole.
The presence of dust is important as it is made of elements that are only produced by nuclear reactions deep inside massive stars, and are then spread around the galaxy when these stars explode as supernovae. This indicates that the gas seen around W2246 has been cycled inside stars in the past – probably in the surrounding galaxies – prior to the start of the galaxy’s current dramatic burst of activity. The new images therefore provide insight not only into the activity in the galaxy as we see it today, but also into its history at even earlier times.
To be visible to ALMA, the bridging dust must be actively heated. This could be done by young stars that also occupy the bridges, or by the radiation from the hugely bright core of W2246. The conditions in the gas within the bridges suggest that even if W2246 is the primary heat source, the gas in the bridges can still collapse under its own gravity to form new stars in dense clouds, which would allow it to be gobbled up by the central black hole to fuel W2246.
From the relative speed and separation of the companion galaxies, it is possible to work out how much mass they contain. We can also estimated that the duration of the current interaction is about 200m years. Together, we used this to determine the rate at which gas must be fed into the black hole, uncovering that it is indeed sufficient to produce the dramatic energy output we see from the object.
However, the details of what happens within the bright compact core of the galaxy as this material rains in, and enters the the black hole (that then heats and drives away material) can’t be seen. Observations on finer scales will be needed to investigate what happens deep in the heart of W2246.
Out with a whimper?
Luckily, further observations using ALMA and the forthcoming James Webb Space Telescope (JWST), scheduled for launch in 2021, will be able to reveal exactly how the gas and dust travels within and is distributed around the galaxies, gets converted into stars and is consumed by the black hole.
Not only will these observations give insight into this most extreme galaxy, it could also help us understand the processes that build more ordinary galaxies, and the conditions required to ignite all galaxies’ most luminous phases.
It’s been great watching W2246. In about 100m years, it will definitely have finished its meal of neighbouring galaxies. It will then lose its sparkle, and another object will take the crown of being the brightest galaxy in the universe. Nothing is forever.
Flat-Eathers aren’t famous for their intelligence or articulation, but even by their standards, a post by Flat-Earth Society member, Varuag, is pushing it.
In a long, barely decipherable post on the The Flat-Earth Society website’s forum, Varuag posits the theory that instead of being shaped like a pancake, The Earth is, in fact, the shape of a donut.
OK. I’m being little mean. Varuag doesn’t ever actually say that he believes this to be fact, instead he says it’s a theory that he thinks can be built upon. He says that The Earth is a torus. According to Wikipedia a torus is “a surface of revolution generated by revolving a circle in three-dimensional space about an axis coplanar with the circle”. In plain English, a three-dimensional donut.
In a series question and answers, Varuag laid his theory out. The first, and most important, question was along the lines of if it’s donut shaped, where’s the hole? Varuag responded that the curvature of light corresponds with the curvature of the torus, making the donut hole invisible (don’t worry, you’re not meant to understand).
Varuag goes on to explain his theory using logic that can barely even be described as pseudo-science. When asked “if I stand on the surface in the middle of the TE (torus earth) and look up, why can’t I see the opposite side of the torus?” He answers (and I quote),
“When you stand in the middle of the TE and look up, the light passes through the first atmosphere it reaches. However, by the time it reaches the second atmosphere (the one to re-enter the atmosphere of the TE) it has diminished enough to be reflected, and gets reflected into space, so you see space.”
So yeah. That about sums up the calibre of this theory. I’ve long ago given up attempting to figure out which parts of flat-earth theory satire and which are earnest. As always, I hope this is a joke but the sheer work gone into it suggests to me that Varuag is serious.
The link to the full thing is below, if you want to waste an hour making yourself less educated.
Panspermia – the hypothesis that life exists throughout the Universe, distributed by space dust, meteoroids, asteroids, comets, planetoids, and also by spacecraft carrying unintended contamination by microorganisms – is nothing new. It’s a theory that has been around for decades.
The University of Hawaii at Manoa is investigating the theory, and trying to get to the heart of elements involved. In a study published in Nature Communications, researchers suggest that phosphate could have been delivered to Earth in its first billion years by meteorites or comets.
The team used the process of infrared spectroscopy to analyze. In this process the team uses an ultra-high vacuum chamber to cool simulated interstellar grains down to -270°C (-450°F). They coat those grains in carbon dioxide and water, and phosphine.
Within the chamber, they expose these grains to radiation which simulates cosmic rays in space. The result is the production of phosphoric acid which is a key ingredient in life here on Earth.
“On Earth, phosphine is lethal to living beings. But in the interstellar medium, an exotic phosphine chemistry can promote rare chemical reaction pathways to initiate the formation of biorelevant molecules such as oxoacids of phosphorus, which eventually might spark the molecular evolution of life as we know it.” says lead author Andrew Turner.
A new project known as the Trillion Planet Survey, is launching a search for directed intelligence in M31 (The Andromeda Galaxy). The project is being run by the University of California, Santa Barbara.
The aim of the Trillion Planet Survey is to try and detect laser signals directed at us from an extraterrestrial civilization in M31. And according to researchers, this is our best target for searching to date, “Andromeda is home to at least one trillion stars, and thus at least one trillion planets. As a result, in surveying M31, we are surveying one trillion planets, and consequently one trillion possible locations of intelligent life. This is an unprecedented number of targets relative to other past SETI searches. ”
Specifically, researchers will be looking for intelligence of “similar or higher class than ours trying to broadcast their presence using an optical beam,” says lead researcher Andrew Stewart, a student at Emory University and a member of Lubin’s group (Lubin is the the lead on the Trillion Planet Survey).
Below you can read the abstract from the Trillion Planet Project:
In realm of optical SETI, searches for pulsed laser signals have historically been preferred over those for continuous wave beacons. There are many valid reasons for this, namely the near elimination of false positives and simple experimental components. However, due to significant improvements in laser technologies and light-detection systems since the mid-20th century, as well as new data from the recent Kepler mission, continuous wave searches should no longer be ignored. In this paper we propose a search for continuous wave laser beacons from an intelligent civilization in the Andromeda galaxy. Using only a 0.8 meter telescope, a standard photometric system, and an image processing pipeline, we expect to be able to detect any CW laser signal directed at us from an extraterrestrial civilization in M31, as long as the civilization is operating at a wavelength we can “see” and has left the beacon on long enough for us to detect it here on Earth. The search target is M31 due to its high stellar density relative to our own Milky Way galaxy. Andromeda is home to at least one trillion stars, and thus at least one trillion planets. As a result, in surveying M31, we are surveying one trillion planets, and consequently one trillion possible locations of intelligent life. This is an unprecedented number of targets relative to other past SETI searches. We call this the TPS or Trillion Planet Survey.
We now know the reason the Sunspot Solar Observatory in New Mexico was shut down last week and the details aren’t pretty.
FBI records obtained by Reuters show that the closure stemmed from an FBI child pornography probe.
The report states that the FBI was “investigating the activities of an individual who was utilizing the wireless internet service of the National Solar Observatory in Sunspot, New Mexico, to download and distribute child pornography.”
The individual in question has been identified as a janitor staffed to maintain the facility, whose laptop was connected to the observatories wifi. The decision was made to shut down the observatory “out of concern that the suspect might pose a danger to other personnel.”
The group that runs the facility, AURA, has stated it is “cooperating with an on-going law enforcement investigation of criminal activity that occurred at Sacramento Peak.”
As we dive into the details, the story begins to get a bit strange:
According to gizmodo, there was a search warrant that claimed hundreds of files of child porn had been downloaded and distributed onto Sunspot’s wifi, of which only one persons activity matched. That computer was seized by the FBI, and that janitor protested his innocence claiming that other people had access to the computer.
Allegedly the janitor began to become erratic and “potentially dangerous” so the FBI made the decision to shut down the observatory for safety.
A report from a New Mexico station KRQE, states that the suspect said it’s “only a matter of time before the facility got hit,” and that he “believed there was a serial killer in the area” that may execute someone in the observatory. Ultimately, this is what may have gotten the facility shut down for the weekend.
The subject in question has yet to be named as he is not yet formally charged.
Reading like something straight out of the newest season of Stranger Things, the Sunspot Solar observatory in the state of New Mexico has been mysteriously shut down and evacuated. The observatory is home to one of the largest active solar telescopes in the world, but was quietly evacuated Thursday the 7th, as FBI agents immediately arrived at the scene.
Public visitors and employees have been banned from the building indefinitely. As if there wasn’t enough mystery around the whole affair, the observatory’s website simply reads “TEMPORARILY CLOSED”.
Even local authorities are baffled. Local law enforcement agents were sent to investigate the scene by Sheriff Benny House, only to find “no specific threat”.
Speaking to Alamogordo City News, Sheriff House was as curious as anyone else.
“The FBI is refusing to tell us what’s going on… We’ve got people up there (at the observatory) that requested us to standby while they evacuated it. Nobody would really elaborate on any of the circumstances as to why. The FBI were up there. What their purpose was nobody will say.”
One week on from the evacuation, and there is still no information about what has happened, which has left the most imaginative of minds going wild with theories. AURA (The Association of Universities for Research in Astronomy) is the company that runs the observatory, but they have done little to clear up the wild rumours that are now surrounding the event.
A spokesperson from AURA, Shari Lifson, simply attributed the event to a “security issue”, but did not elaborate any further, which is interesting considering that the FBI is directing all inquiries to AURA. On speaking with Alamogordo Lifson said “I am actually not sure (why the facility was evacuated), but it will stay vacated until further notice.”
As if this event in itself was not mysterious enough, the local post office has also been shut down, with no information as to why reaching the ears of employees.
“Right now, what we’re told is that they’ve evacuated the area. We haven’t been told why or when that expires,” spokesman with USPS Rod Spurgeon told ABC 7.
Right now, the observatory and its goings-on are shrouded in mystery. The only hint that we might one day get some answers can be found on Sunspot Observatory’s website:
“With the excitement this closure has generated, we hope you will come and visit us when we do reopen, and see for yourself the services we provide for science and public outreach in heliophysics.”
Watch this space……
Astronomers have had a blockbuster year.
In addition to tracking down a cosmic source of neutrinos, they have detected the merger of two city-sized neutron stars, each more massive than the sun.
But what is multimessenger astronomy?
In our daily lives, we interpret the world around us based on different signals, such as sound waves, light (a type of electromagnetic wave) and skin pressure. Each of these signals may be carried by a different “messenger.” New messengers lead to new insights. So astronomers have eagerly welcomed a new set of messengers to their science.
For most of the history of astronomy, scientists primarily studied signals transmitted by one messenger, electromagnetic radiation. These waves, which move through space and time, are described by their wavelengths or the amount of energy found in their particles, the photons.
Radio waves have photons with the lowest amount of energy and the longest wavelengths, followed by infrared and optical light at intermediate energies and wavelengths. X-rays and gamma-rays have the shortest wavelengths and the highest energy.
But scientists study others messengers too:
- Cosmic rays: charged atomic particles and nuclei travelling near the speed of light.
- Neutrinos: uncharged particles that see most of the universe as transparent.
- Gravitational waves: wrinkles in the very fabric of space and time.
And while some fields in astronomy have explored these messengers for years, astronomers have only recently observed events from well beyond the Milky Way with more than one messenger at the same time. In just a few months, the number of sources where astronomers can piece together the signals from different messengers doubled.
Like a walk on the beach
Multimessenger astronomy is a natural evolution of astronomy. Scientists need more data to put together a complete picture of the objects they study and match the theories they develop with their observations.
Astronomers have combined different wavelengths of photons to piece together some of the mysteries of the universe. For example, the combination of radio and optical data played a major role in determining that the Milky Way is a spiral galaxy in 1951.
And astronomy continues to reveal great results about our universe using just one messenger, photons. So if multimessenger astronomy is just an evolutionary step of an incredible history of successes, does that mean it’s just a new buzzword?
We don’t think so.
Imagine you are walking along an ocean beach. You are enjoying the sight of an incredible sunset, hearing the rolling waves, feeling the sand beneath your feet and smelling the salty air. Your combined senses form a more complete experience.
With multimessenger astronomy, we hope to learn more from the universe by combining multiple messengers, just as we combine sight, hearing, touch and smell.
But it’s not always a picnic
The cultures of astronomers and particle physicists represent different approaches to science. In multimessenger astronomy, these cultures collide.
Astronomy is an observational field and not an experiment. We study astronomical objects that change over time (time-domain astronomy), which means we often have only one chance to observe a transient astronomical event.
Until recently, most time-domain astronomers worked in small teams, on many projects at once. We use resources like The Astronomer’s Telegram or the Gamma-ray Coordination Network to rapidly communicate results, even before submitting scientific papers.
Since most of the expected sources of multimessenger signals are transient astronomical events, it’s a huge effort to capture the messengers besides photons.
Particle physicists have led the way in creating large international collaborations to tackle their hardest problems, including the Large Hadron Collider, the IceCube Neutrino Observatory and the Laser Interferometer Gravitational-Wave Observatory (LIGO). Corralling hundreds to thousands of researchers to work towards common goals requires comprehensive identification of roles, strict communication guidelines and many teleconferences.
The need to respond to rapid changes in a multimessenger source and the huge effort to capture multimessenger signals means astronomy and particle physics must merge towards one another to elicit the best of both cultures.
The benefits of multimessenger astronomy
While multimessenger astronomy is an evolution of what astronomers and particle physicists have done for decades, the combined results are intriguing.
The detection of gravitational waves from merging neutron stars confirmed that these collisions made a large fraction of the gold and platinum on Earth (and throughout the universe). It also showed how these collisions give rise to (at least some) short gamma-ray bursts — the origin of these explosive events has been a huge open question in astronomy.
The first association of a neutrino with a single astronomical source provided a glimpse into how the universe makes its most energetic particles. Multimessenger astronomy is revealing details about some of the most extreme conditions in our universe.
The multimessenger perspective is already yielding more than the sum of its parts — and we can expect to see more surprising discoveries in the future. Elite teams across Canada are already contributing to the growth of this young field, and multimessenger astronomy promises to play a major role in our next decade of astronomical research in Canada — and across the world.
A signal caused by the very first stars to form in the universe has been picked up by a tiny but highly specialised radio telescope in the remote Western Australian desert.
Details of the detection are revealed in a paper published today in Nature and tell us these stars formed only 180 million years after the Big Bang.
It’s potentially one of the most exciting astronomical discoveries of the decade. A second Nature paper out today links the finding to possibly the first detected evidence that dark matter, thought to make up much of the universe, might interact with ordinary atoms.
Tuning in to the signal
This discovery was made by a small radio antenna operating in the band of 50-100Mhz, which overlaps some well known FM radio stations (which is why the telescope is located in the remote WA desert).
What has been detected is the absorption of light by neutral atomic hydrogen gas, which filled the early universe after it cooled down from the hot plasma of the Big Bang.
At this time (180 million years after the Big Bang) the early universe was expanding, but the densest regions of the universe were collapsing under gravity to make the first stars.
The formation of the first stars had a dramatic effect on the rest of the universe. Ultraviolet radiation from them changed the electron spin in the hydrogen atoms, causing it to absorb the background radio emission of the universe at a natural resonant frequency of 1,420MHz, casting a shadow so to speak.
Now, 13 billion years later, that shadow would be expected at a much lower frequency because the universe has expanded nearly 18-fold in that time.
An early result
Astronomers had been predicting this phenomenon for nearly 20 years and searching for it for ten years. No one quite knew how strong the signal would be or at what frequency to search.
Most expected it would take quite a few more years post 2018.
But the shadow was detected at 78MHz by a team led by astronomer Judd Bowman from Arizona State university.
Amazingly this radio signal detection in 2015-2016 was done by a small aerial (the EDGES experiement), only a few metres in size, coupled to a very clever radio receiver and signal processing system. It’s only been published now after rigorous checking.
This is the most important astronomical discovery since the detection of gravitational waves in 2015. The first stars represent the start of everything complex in the universe, the beginning of the long journey to galaxies, solar systems, planets, life and brains.
Detecting their signature is a milestone and pinning down the exact time of their formation is an important measurement for cosmology.
This is an amazing result. But it gets better and even more mysterious and exciting.
Evidence of dark matter?
The signal is twice as strong as expected, which is why it has been detected so early. In the second Nature paper, astronomer Rennan Barkana, from the Tel Aviv University, said it is quite hard to explain why the signal is so strong, as it tells us the hydrogen gas at this time is significantly colder than expected in the standard model of cosmic evolution.
Astronomers like to introduce new kinds of exotic objects to explain things (e.g. super massive stars, black holes) but these generally produce radiation that makes things hotter instead.
How do you make the atoms colder? You have to put them in thermal contact with something even colder, and the most viable suspect is what is known as cold dark matter.
Cold dark matter is the bedrock of modern cosmology. It was introduced in the 1980s to explain how galaxies rotate – they seemed to spin much faster than could be explained by the visible stars and an extra gravitational force was needed.
We now think that dark matter has to be made of a new kind of fundamental particle. There is about six times more dark matter than ordinary matter and if it was made of normal atoms the Big Bang would have looked quite different to what is observed.
As for the nature of this particle, and its mass, we can only guess.
So if cold dark matter is indeed colliding with hydrogen atoms in the early universe and cooling them, this is a major advance and could lead us to pin down its true nature. This would be the first time dark matter has demonstrated any interaction other than gravity.
Here comes the ‘but’
A note of caution is warranted. This hydrogen signal is very difficult to detect: it is thousands of times fainter than the background radio noise even for the remote location in Western Australia.
The authors of the first Nature paper have spent more than a year doing a multitude of tests and checks to make sure they have not made a mistake. The sensitivity of their aerial needs to be exquisitely calibrated all across the bandpass. The detection is an impressive technical achievement but astronomers worldwide will be holding their breath until the result is confirmed by an independent experiment.
If it is confirmed then this will open the door to a new window on the early universe and potentially a new understanding of the nature of dark matter by providing a new observational window in to it.
This signal has been detected coming from the whole sky, but in the future it can be mapped on the sky, and the details of the structures in the maps would then give us even more information on the physical properties of the dark matter.
More desert observations
Today’s publications are exciting news for Australia in particular. Western Australia is the most radio quiet zone in the world, and will be the prime location for future mapping observations. The Murchison Widefield Array is in operation right now, and future upgrades could provide exactly such a map.
This is also a major science goal of the multi-billion dollar Square Kilometre Array, located in Western Australia, that should be able to provide much greater fidelity pictures of this epoch.
It is extremely exciting to look forward to a time when we will be able to reveal the nature of the first stars and to have a new approach via radio astronomy to tackle dark matter, which has so far proved intractable.
Let’s hope the governments of the world, or at least Australia, can keep the frequency of 78MHz clean of pop music and talk shows so we can continue to observe the birth of the universe.
Gamma ray bursts, intense explosions of light, are the brightest events ever observed in the universe – lasting no longer than seconds or minutes. Some are so luminous that they can be observed with the naked eye, such as the burst “GRB 080319B” discovered by NASA’s Swift GRB Explorer mission on March 19, 2008.
But despite the fact that they are so intense, scientists don’t really know what causes gamma ray bursts. There are even people who believe some of them might be messages sent from advanced alien civilisations. Now we have for the first time managed to recreate a mini version of a gamma ray burst in the laboratory – opening up a whole new way to investigate their properties. Our research is published in Physical Review Letters.
One idea for the origin of gamma ray bursts is that they are somehow emitted during the emission of jets of particles released by massive astrophysical objects, such as black holes. This makes gamma ray bursts extremely interesting to astrophysicists – their detailed study can unveil some key properties of the black holes they originate from.
The beams released by the black holes would be mostly composed of electrons and their “antimatter” companions, the positrons – all particle have antimatter counterparts that are exactly identical to themselves, only with opposite charge. These beams must have strong, self-generated magnetic fields. The rotation of these particles around the fields give off powerful bursts of gamma ray radiation. Or, at least, this is what our theories predict. But we don’t actually know how the fields would be generated.
Unfortunately, there are a couple of problems in studying these bursts. Not only do they last for short periods of time but, most problematically, they are originated in distant galaxies, sometimes even billion light years from Earth (imagine a one followed by 25 zeroes – this is basically what one billion light years is in metres).
That means you rely on looking at something unbelievably far away that happens at random, and lasts only for few seconds. It is a bit like understanding what a candle is made of, by only having glimpses of candles being lit up from time to time thousands of kilometres from you.
World’s most powerful laser
It has been recently proposed that the best way to work out how gamma ray bursts are produced would be by mimicking them in small-scale reproductions in the laboratory – reproducing a little source of these electron-positron beams and look at how they evolve when left on their own. Our group and our collaborators from the US, France, UK, and Sweden, recently succeeded in creating the first small-scale replica of this phenomenon by using one of the most intense lasers on Earth, the Gemini laser, hosted by the Rutherford Appleton Laboratory in the UK.
How intense is the most intense laser on Earth? Take all the solar power that hits the whole Earth and squeeze it into a few microns (basically the thickness of a human hair) and you have got the intensity of a typical laser shot in Gemini. Shooting this laser onto a complex target, we were able to release ultra-fast and dense copies of these astrophysical jets and make ultra-fast movies of how they behave. The scaling down of these experiments is dramatic: take a real jet that extends even for thousands of light years and compress it down to a few millimetres.
In our experiment, we were able to observe, for the first time, some of the key phenomena that play a major role in the generation of gamma ray bursts, such as the self-generation of magnetic fields that lasted for a long time. These were able to confirm some major theoretical predictions of the strength and distribution of these fields. In short, our experiment independently confirms that the models currently used to understand gamma ray bursts are on the right track.
The experiment is not only important for studying gamma ray bursts. Matter made only of electrons and positrons is an extremely peculiar state of matter. Normal matter on Earth is predominantly made of atoms: a heavy positive nucleus surrounded by clouds of light and negative electrons.
Due to the incredible difference in weight between these two components (the lightest nucleus weighs 1836 times the electron) almost all the phenomena we experience in our everyday life comes from the dynamics of electrons, which are much quicker in responding to any external input (light, other particles, magnetic fields, you name it) than nuclei. But in an electron-positron beam, both particles have exactly the same mass, meaning that this disparity in reaction times is completely obliterated. This brings to a quantity of fascinating consequences. For example, sound would not exist in an electron-positron world.
So far so good, but why should we care so much about events that are so distant? There are multiple reasons indeed. First, understanding how gamma ray bursts are formed will allow us to understand a lot more about black holes and thus open a big window on how our universe was born and how it will evolve.
But there is a more subtle reason. SETI – Search for Extra-Terrestrial Intelligence – looks for messages from alien civilisations by trying to capture electromagnetic signals from space that cannot be explained naturally (it focuses mainly on radio waves, but gamma ray bursts are associated with such radiation too).
Of course, if you put your detector to look for emissions from space, you do get an awful lot of different signals. If you really want to isolate intelligent transmissions, you first need to make sure all the natural emissions are perfectly known so that they can excluded. Our study helps towards understanding black hole and pulsar emissions, so that, whenever we detect anything similar, we know that it is not coming from an alien civilisation.
When LIGO, the Laser Interferometer Gravitational-Wave Observatory, first detected gravitational waves from merging black holes, it opened up a new window in astrophysics and provided the most powerful confirmation yet of Einstein’s theory of general relativity. Now LIGO has done it again, together with the Virgo interferometer, this time by observing merging neutron stars – something astrophysicists had known must happen but had never been able to detect definitively until now.
Observing two neutron stars smash together is important for much more than just the thrill of discovery. This news may confirm a longstanding theory: that some gamma-ray bursts (GRBs for short), which are among the most energetic, luminous events in the universe, are the result of merging neutron stars. And it is in the crucible of these mergers that most heavy elements may be forged. Researchers can’t produce anything like the temperatures or pressures of neutron stars in a laboratory, so observation of these exotic objects provides a way to test what happens to matter at such extremes.
Astronomers are excited because for the first time they have gravitational waves and light signals stemming from the same event. These truly independent measurements are separate avenues that together add to the physical understanding of the neutron star merger.
Gravitational waves just one part of this news
The LIGO project has thus far announced the detection of four mergers of binary black holes – observed via the gravitational waves they emitted. These are ripples in the fabric of spacetime propagating in all directions, like waves emanating out from a pebble dropped in a pond. Encoded in the gravitational wave signal is information about the pre- and post-merger masses of the objects. Black holes are much more massive than neutron stars, so the energy they release as gravitational waves is much higher. Because light cannot escape from a black hole, you expect (and see) no light from these mergers.
The merger of neutron stars should produce both a gravitational wave and a short gamma-ray burst signal. These brief, incredibly intense flashes of gamma-ray light are seen from galaxies across the universe. They come in two types, classified by their duration. Short GRBs are thought to come from the mergers of neutron stars, while long GRBs are known to be coincident with supernovas.
Key to unlocking the mystery of any astronomical object is knowing its distance. In recent years, astronomers have identified the host galaxies of a handful of short GRBs. Determining those galaxies’ distances allows astronomers to calculate the power emitted in gamma-rays during the burst, and to determine (or rule out) physical scenarios that could produce that power.
But for LIGO to detect two neutron stars spiraling in toward each other and merging, it would need to happen relatively nearby – within around 250 million light-years. That such an event was not detected during the first year and a half of LIGO observations already lets astronomers place a constraint on how frequently they happen in the nearby universe.
So the rumor of a merging neutron star detection by LIGO with a coincident short gamma-ray burst (GRB170817A) seen by NASA’s Fermi Gamma-ray Space Telescope spread through the astronomical community like wildfire this past summer. Astronomers watched from the sidelines as most of the major telescopes in (and above) the world slewed toward an otherwise unremarkable old, nearby (130 million light-years) elliptical galaxy named NGC 4993.
What we’ve known about neutron stars
Most stars end their lives relatively calmly; no longer supported by the fusion of hydrogen into helium, their outer layers glide slowly off into space while their cores collapse to the very limits allowed by normal matter – burning embers the size of the Earth called white dwarf stars.
For the rare stars whose masses are a bit higher, 10 to 20 times that of the sun, the picture is a bit different. These stars die the way they lived: quickly and violently, ejecting their outer layers as supernovas and leaving behind something far stranger – a neutron star.
The details of this story were worked out in 1930 by then 19-year-old Indian astrophysicist Subrahmanyan Chandrasekhar. He determined precisely how far you can compress normal matter before the relentless pressure of gravity forces electrons into the nuclei of their atoms where they merge with protons to form neutrons. Instead of an Earth-sized remnant, a massive star’s core collapses further to become a highly compressed ball of exotic matter as small as a city but whose mass can be twice that of the sun.
Neutron stars rotate incredibly rapidly. The collapse from millions to tens of kilometers in extent increases their spin due to conservation of angular momentum, like an ice skater pulling in her arms. While the parent star may have rotated once a month, a newly born neutron star can spin hundreds of times per second.
This rapid spinning led to their initial discovery. 50 years ago, Antony Hewish and Jocelyn Bell Burnell discovered the first radio pulsar: a neutron star emitting radio waves which appear to observers as pulses as the star rotates, like a lighthouse. Hewish would win the 1974 Nobel Prize in physics for this discovery, while Bell Burnell was controversially overlooked.
But what are neutron stars really made of? Are they neutrons all the way through or can they break down further again, into what physicists call “quark soup”? The answer lies in measuring their size. A larger neutron star is mostly neutrons, a smaller star has a more complicated interior made of quarks – the building blocks of protons and neutrons. Untangling how this works is important for our understanding of the fundamental properties of subatomic particles. A new telescope on the International Space Station aims to address this question by targeting neutron stars and measuring their sizes.
When neutron stars merge
Over half of all stars are part of binary pairs, and massive stars are more likely to occur in binaries. These pairs of massive stars will co-evolve, and when they die, a pair of neutron stars may remain, orbiting one another.
An orbiting pair of neutron stars loses energy by emitting gravitational waves, and over time this loss of energy will cause them to migrate closer and closer until they eventually collide. While the eventual merger is nearly instantaneous, the gradual inspiral takes tens to hundreds of millions of years, so we expect to see mergers in more evolved galaxies – like NGC 4993, for instance – rather than those that are still rapidly forming new stars.
For decades, it has been suggested that merging neutron stars may provide a mechanism for producing most of the elements on the periodic table heavier than iron. These so-called r-process elements must form in a neutron-rich environment, and have been formed by humans only during the explosion of nuclear bombs.
The signal from such an event is suspected to rapidly cascade through the electromagnetic spectrum, from gamma-rays to X-rays, visible light and infrared. Known as kilonovas, these afterglows have been seen from past short GRBs.
Finally all the pieces fall into place with this gravitational wave detected by the LIGO and Virgo teams, and all the subsequent supporting observations made by astronomers around the world. We know the neutron star masses, the duration of the event, and the distance of the host galaxy. This not only confirms the hypothesis that merging neutron stars produce short GRBs; it lays the foundation for astronomers to produce models of the merger backed both by fundamental physics and real world observations. It’s a rare event to see something new for the first time, and rarer still that it confirms a longstanding theory.
Scientists now know that the universe contains at least two trillion galaxies. It’s a mind-scrunchingly big place, very different to the conception of the universe we had when the world’s major religions were founded. So do the astronomical discoveries of the last few centuries have implications for religion?
Over the last few decades, a new way of arguing for atheism has emerged. Philosophers of religion such as Michael Martin and Nicholas Everitt have asked us to consider the kind of universe we would expect the Christian God to have created, and compare it with the universe we actually live in. They argue there is a mismatch. Everitt focuses on how big the universe is, and argues this gives us reason to believe the God of classical Christianity doesn’t exist.
To explain why, we need a little theology. Traditionally, the Christian God is held to be deeply concerned with human beings. Genesis (1:27) states: “God created mankind in his own image.” Psalms (8:1-5) says: “O Lord … What is man that You take thought of him … Yet You have made him a little lower than God, And You crown him with glory and majesty!” And, of course, John (3:16) explains God gave humans his son out of love for us.
These texts show that God is human-oriented: human beings are like God, and he values us highly. Although we’re focusing on Christianity, these claims can be found in other monotheistic religions, too.
Not a human-oriented universe
If God is human-oriented, wouldn’t you expect him to create a universe in which humans feature prominently? You’d expect humans to occupy most of the universe, existing across time. Yet that isn’t the kind of universe we live in. Humans are very small, and space, as Douglas Adams once put it, “is big, really really big”.
Our own planet is 150m kilometres away from the sun. Earth’s nearest stars, the Alpha Centauri system, are four light years away (that’s around 40 trillion kilometres). Our galaxy, the Milky Way, contains anywhere from 100 to 400 billion stars. The observable universe contains around 300 sextillion stars. Humans occupy the tiniest fraction of it. The landmass of planet Earth is a drop in this ocean of space.
To paraphrase Adams, the universe is also really, really old. Perhaps over 13 billion years old. Earth is around four billion years old, and humans evolved around 200,000 years ago. Temporally speaking, humans have been around for an eye-blink.
Clearly, there is a discrepancy between the kind of universe we would expect a human-oriented God to create, and the universe we live in. How can we explain it? Surely the simplest explanation is that God doesn’t exist. The spatial and temporal size of the universe gives us reason to be atheists.
As Everitt puts it:
The findings of modern science significantly reduce the probability that theism is true, because the universe is turning out to be very unlike the sort of universe which we would have expected, had theism been true.
The fact that atheism is the simplest reply to the mismatch doesn’t mean that other explanations aren’t possible. Perhaps God exists but his motives for not creating humans sooner, or on a bigger scale, are unknowable. The divine is, after all, mysterious.
Perhaps the swathes of space strung with gossamer nebulae serve some aesthetic purpose, beauty wrought on an inhuman scale. Or, perhaps, God exists but isn’t as human-oriented as we thought. Perhaps God values rocks and cosmic dust more highly than humans.
The problem with these rival explanations is that, as they stand, they are unsatisfying. They hint at reasons why God might create tiny humans in a gargantuan place but are a million miles away from fully explaining why. The weight of galaxies, and the press of years, seem to sweep us towards atheism.
Bright shooting stars are one of nature’s great wonders. Like the one in the main image, which was visible from Devon in the south-west of England in June, these fireballs are caused by space rocks hitting Earth’s atmosphere. The friction forces them to slow down, producing a tremendous amount of heat at the same time. If the rock is big enough, a fragment will survive this fiery transition and fall to Earth as a meteorite.
Planetary scientists study these rocks to extract clues as to how our solar system formed. But this work is complicated by the fact that we don’t know where in the solar system most of Earth’s 50,000 or so meteorites came from.
To improve this situation, you have to determine a new fireball’s orbit once it breaches Earth’s atmosphere. This means observing it from multiple angles. You then ideally want to recover the meteorite before the weather changes the chemistry of the sample – usually in the first shower of rain. A new network of cameras is being set up in the UK to help in this endeavour, phase two of a global network that started five years ago in Australia.
Meteorites are arriving from outer space all the time. About 50 tonnes of extraterrestrial material enters Earth’s atmosphere each year. Most are sand-sized particles known as cosmic dust, including the majority of the Perseid meteor shower that took place earlier in August.
But even over a relatively small space like the UK, about 20 meteorites of a searchable size land each year – of which the Devon fireball was a good example. Most are barely 10g, about the size of a six-sided dice. Two or three will be bigger; usually up to a kilogram in mass or the size of a tennis ball.
This is but a remnant of the 6,000 to 20,000 meteorites in the same size range that we see each year in the land mass of the world as a whole. Yet observing and finding these is still no mean feat. To date, only around 30 meteorites have been recovered after their fireball was observed. This has mostly been through remote camera networks including in Canada, France, the Czech Republic, Finland and Australia.
Such networks are continuously imaging the night sky over a huge area, which is ideal for tracking orbits back to space and reaching the landing site fast. I used to work as a researcher for the Desert Fireball Network in Australia. Since it was set up five years ago, its 52 cameras have found four meteorites.
The project to extend the Desert Fireball Network has already seen three high-resolution cameras installed in different parts of England in recent months, along with sophisticated image-processing software. A further seven will be in place by next summer, in a collaboration between Imperial College London, University of Glasgow, the Open University, the Natural History Museum and Curtin University in Perth, Australia.
The new network will track any fast-moving object flying across the skies above the UK, including things like satellites. It will complement an existing network of 30 video cameras called the UK Meteor Observation Network, which is already run by citizen scientists to spot fireballs and smaller meteors. UKMON focuses on capturing images rather than meteorite recovery. The two operations will share data, enhancing one another’s abilities. There are also plans to extend the new network to the US, South America, New Zealand and Saharan Africa in the next few years.
The challenges facing the UK operation are quite different to those in Australia. Where the Australian network needs to be able to survive unattended in the brutal desert heat, the UK cameras will work in a distinctly colder, wetter climate.
They will have to contend with light pollution, unpredictable weather and significant cloud cover, reducing the number of nights they will be able to take images. But most problematic of all is the ground itself. The Australian outback is ideal for meteorite hunting: uniformly red and with very little vegetation, meaning you can spot a little black rock from several hundred metres. By contrast, the UK’s lush vegetation and woodland can easily camouflage meteorites.
Yet the UK network also has advantages. Most cameras will be within a day’s drive and connected to the internet to provide instant warnings when a camera needs some tender loving care – the Australian cameras tend to be on rougher terrain that takes longer to reach and many are not internet-connected. At the same time, the UK population density is such that quite a lot of people are likely to spot a large fireball and take pictures on their smartphones.
Apps upside your head
Unlocking the assistance of these 65m independent autonomous observatories in the UK is part of the project. The Australian fireball team has developed an app in conjunction with US software consultancy ThoughtWorks. Known as Fireballs in the Sky and free for Apple and Android phones alike, it allows anyone to become a citizen scientist. Users can report any fireball, as well as getting details of the next big meteor shower and where in the sky to look for it – and here’s a grab of what it looks like.
The app is already up and running. In fact, the latest recovered meteorite in Australia, called Dingle Dell, was initially observed by a citizen scientist using it.
This made it possible to find the pristine meteorite before delicate minerals inside it were irreparably altered or washed away by rain, revealing extraterrestrial salts formed early in the solar system that usually quickly disappear on the surface of Earth. These could potentially tell us things about the origins of life and water on our planet.
These kinds of exciting discoveries give a taste of why it will be a race against time to recover the first meteorite tracked by the UK network. So do we have any volunteers?
Luke Daly, Research Associate, School of Geographical and Earth Sciences, University of Glasgow; Gareth Collins, Reader in Planetary Science, Imperial College London, and Martin Suttle, Researcher in Meteoritics and Planetary Science, Imperial College London
The stars are projectors. Well, at least according to Modest Mouse.
Humans have a pretty interesting relationship with the starlight that emits from the night sky.We make wishes upon stars. We sometimes even say that our fate is written in them. Stars have acted as a muse for countless artists, from Vincent Van Gogh to Walt Whitman.
I decided to write this very article under the night sky. Trust me, it’s way less romantic than it sounds. I’m just an insomniac with a MacBook. Still, our fascination with the balls of gas that gleam and glitter in the night is undeniable.
So, what are the different types of stars? From your backyard, they may look more or less identical, some shining slightly brighter than others. You’re lucky to see them at all, apparently, thanks to rampant light pollution.
James Madison University
Before we jump in all starry-eyed, we want to note that there are several different ways to classify stars. From noting spectral types and chemical composition, to luminosity classes and temperature, astronomers have a pretty complex organizational system in place to categorize those bright balls in the night sky that we make wishes on.
The work of American astronomer/badass Annie Cannon was especially crucial to the development of OBAFGKM, a kind of mnemonic astronomers use to remember spectral type letters. OBAFGKM is most often referred to as “Oh! Be A Fine Girl/Guy – Kiss Me!”. I know I said that writing this article under the stars wasn’t romantic, but wow, things are definitely heating up.
Okay, onto the main event. Let’s go stargazing.
The prefix to this little wonder gives away much of its meaning.
The word “proto-” means first or original, and is aptly used to describe this star. Just as human beings begin to grow from a stage of infancy, stars begin their celestial journey as protostars.
The stellar nursery, aka the molecular clouds where stars form, is where these baby stars can be found. Just how long do protostars stay cosmic newborns? A cool 100, 000 years.
Observed to be born in clusters, prepubescent stars are quite social. When it comes to looking at the life cycle of stars, Protostars are considered to be the beginning of things, so it only makes sense that they’re our first stop on our stellar sightseeing tour.
Sentimental Heart via WordPress
2. Main Sequence Star
A whopping 90% of all stars in the universe fall under this category of star, so the next time you make a wish under the night sky, it’s probably on one of these.
Just because they’re common doesn’t mean they are uninteresting.
They can range from a tenth the size of the sun to nearly 200 times as large! Yes, even our own sun is a main sequence star (specifically, a yellow dwarf). This category of the stellar life-cycle also includes the Red Dwarf Star, which you can read about in the very next section. Convenient, I know.
3. Red Dwarf Star
Half as massive as the sun, a Red Dwarf can last 80 to 100 billion years. It is cool, very faint, and small. Amongst all main sequence stars, the red dwarf is the most common in the milky way, but due to luminosity, they’re actually pretty difficult to see.
Long-living and too dim for the naked eye to observe from Earth, the Red Dwarf is 7.5 to 50 percent the mass of the sun.
4. White Dwarf Star
These ancient stars are also referred to as a degenerate dwarf star (ouch).
Stars with low to medium mass, less than 8 times the mass of the sun, eventually become these degenerate stars.
White Dwarfs are incredibly dense stars who fuse hydrogen within their cores into helium in order to survive. They’re essentially just burned-out cores of collapsed stars.
Think of them as the solar system’s aging stars, the evolutionary endpoint to an awesome cosmic journey.
5. T Tauri Star
In stellar terms, the T Tauri Star is a cosmic toddler.
100, 000 to 10 million years old, they rest over 400 light years away and are characterized by erratic changes in brightness. These pre-main sequence stars can have intense stellar winds and are in the process of gravitational contraction.
They weigh under 3 solar masses. Not a protostar, not yet a main sequence star, T Tauri Stars are actually considered to be a kind of pre-main sequence star.
6. Supergiant Stars
As the name implies, these are truly enormous stars. In fact, they’re the largest in the universe.
They make the sun look puny in comparison. They can be thousands of times larger and have a much larger mass than our own sun. Enormous and incredibly hot, when they reach the end of their life they explode into a supernova, which produces either a black hole or a neutron star.
Anyone else think of this song when they read the word supernova?
7. Neutron Stars
Okay, so thanks to the last entry, we know that when giant stars die, they form one of these.
A Neutron star is essentially a collapsed core of a large star, the consequence of supernova explosion and gravitational collapse.
Don’t get them mixed up with a black hole, though. They’re slightly different. If a Neutron star was denser, it would collapse into a black hole.
This may sound pretty morbid, but… isn’t stellar death just incredible?
Galaxy Monitor thinks so.
Our stargazing date has come to a close.
How well can you see the stars from your own backyard? What phrase other than “Oh Be A Fine Guy/Girl, Kiss Me” can you think of to remember the spectral type acronym OBAFGKM?
Let us know by joining our Facebook community.
From asteroids to the best in television science fiction, we’d love to chat. ✨
Lon Lee Illustrations
A shooting black hole is a commonly used term for the scientific event known as a ‘black hole flare’. A black hole flare (or shooting black hole) is when a super massive black hole shoots or erupts beams of X-Ray light. This was observed in 2014, when NASA saw an object coming out of a black hole for the first time ever.
How A Shooting Black Hole Occurs
The black hole’s corona (seen as a purple hue in the below diagram) is responsible for the flare. As the corona shifts, it builds up an immense amount of static energy which causes it to become brighter and eventually release an x-ray emission that can be seen by telescopes on Earth.
As the corona shifts, we see the effect of relativistic boosting. This means that the x-ray light becomes brightened on the side in which the shift has occurred – that is facing towards us. If the shift happened on a curve facing away from us, it would appear as a dimmer object.
Markarian 335, Observed Shooting Black Hole
NASA located an unusual signal in 2014 when the Nuclear Spectroscopic Telescope Array, or NuSTAR picked up an x-ray flare from a black hole in a distant galaxy. This was the first time the event was recorded, and this allowed for astronomers to posit that a shifting corona could lead to a shooting black hole.
Around four decades ago, astronomers became aware that our galaxy, the Milky Way, was moving through space at a much faster rate than expected.
At 2.2-million kilometres an hour, the speed of the Milky Way through the Cosmos is 2,500 times faster than a cruising airliner; 55 times more than the escape velocity from Earth; and a factor of two greater than even the galaxy’s own escape velocity!
But where this motion comes from is a mystery.
The Big Bang theory of our origin tells us that every point in the universe should be flying apart from every other point. Nevertheless, galaxies on either side of us should be moving at similar recession velocities, which should result in no net motion in the Milky Way’s frame of reference.
Net motion can arise from nearby clumps in the distribution of matter, like a massive cluster of galaxies. The additional gravitational attraction of such a galaxy cluster can slow down, and even reverse, the expansion of the universe in its immediate vicinity.
But no such cluster is obvious in the direction of the Milky Way’s motion. There is an excess of galaxies in the general vicinity, and an excess of radiation visible in X-ray telescopes. But nothing that in any way seems large enough to explain the results.
So are we seeing an over-density of pure dark matter? Or is the current theory of the origin of mass and motion incorrect? Astronomer Alan Dressler, of the Carnegie Institution, used the former explanation, famously dubbing the missing concentration of matter the “Great Attractor”.
But another explanation may lie in the fact that the inferred direction of the missing matter is not too far away from the direction of the Coalsack nebula, which lies deep within our own Milky Way.
The hidden attractor
Could our own Milky Way be moving through space like an edge-on spinning disc, obscuring the very source of a distant gravitational attractor? Could there be a super-massive cluster of galaxies (it would need to be the equivalent of 10,000 Andromeda galaxies) that is somehow being missed because its being obscured by the dense layer of dust associated with the thin disc of the Milky Way?
With that in mind, in the late 1990s, our team began using an innovative instrument on the iconic Parkes telescope, in New South Wales, simply known as the Parkes multibeam receiver. The unique sensitivity and field of view of this receiver allowed us to make progressively more sensitive radio surveys of the sky.
These surveys were made by tuning the receiver to what is known as the 21cm line of neutral hydrogen. Although a weak line, the sensitivity of the receiver was such that thousands of galaxies could be detected in “blind” surveys.
Moreover, at radio wavelengths, radiation passes straight through the dust layer in the Milky Way. The Milky Way essentially becomes invisible.
The HI Parkes All-Sky Survey (HIPASS) provided the first shallow survey of the whole southern sky. In fact, HIPASS was the first sensitive sky survey for extragalactic hydrogen ever made by any telescope. But nothing unexpected was found behind the Milky Way.
Other shallow surveys by our team targeted the Milky Way itself. Only a mild galaxy over-density was seen.
But it was recognised that deeper observations were needed. Theoretical models (particularly the so-called Lambda-cold-dark-matter model) only come under suspicion if nothing is found within a distance of 200 million light years.
Therefore, a long series of deeper observations of the local universe behind the disc and bulge of the Milky Way was conducted, again with the Parkes telescope.
From out of the data
These finished in the mid-2000s. Due to the extra difficulty of analysing radio data in the Milky Way (there is extra noise created by cosmic rays in our galaxy) and the dispersal of our team, it took until last year for all the data to be fully analysed and submitted for publication.
Within five degrees of the Milky Way’s disc, we found altogether 883 galaxies plus a further 77 in the two bits of the northern Milky Way, visible from Parkes. Only a small number of these galaxies had a previous optical redshift and therefore distance estimate.
But when we looked at data from new infrared surveys, combined with data from our own brand-new deep infrared survey (infrared or heat radiation passes much more easily through dust), we were able to confirm stellar counterparts for almost 80% of the galaxies. The rest are too deeply embedded in the Milky Way to be confirmed with any existing optical or infrared telescope.
It would be nice to think that it was because the mystery has deepened even more. We did find new galaxies, clusters of galaxies and new strands in the cosmic web. Just not enough to explain our motion, so there is still the mystery of what is the “Great Attractor” that has this pull on our Milky Way.
I think most of the excitement was generated by the simple act of unveiling the universe a little bit more, like the early explorers completing maps of the blank southern hemisphere.
So what comes next? It just so happens that Australian astronomers are in prime position to further explore structure and motions in the nearby universe. Radio surveys such as CAASTRO’s 2MTF survey, which also uses the Parkes telescope to calculate galaxy distances, are already making new contributions.
Better still will be the WALLABY survey, for which I am co-principal investigator with Dr Baerbel Koribalski, to be executed with the new CSIRO Australian SKA Pathfinder (ASKAP) telescope, starting later this year.
This will allow us to make massive inroads into the detailed exploration of the radio universe, as will the Square Kilometre Array (SKA) itself. At optical wavelengths, the Australian Astronomical Observatory and the ANU are leading a new survey, called TAIPAN, which will target elliptical galaxies to explore more distant regions.
Theorists are also exploring whether the space-time metric we use to describe the universe may no longer be valid, and whether general relativity itself may need modification on large scales.
It’s early days yet, and major shifts in the cosmological paradigm require incontrovertible evidence. Nevertheless, the mystery behind the Great Attractor is an enduring one and may not be fully understood for a few more years.
This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!
What started the Big Bang? – Pippi, 8, Canberra.
This is one of the two questions I get asked a lot (the other one is: do aliens exist?) Both are very good questions! Pippi, the short answer is that we do not know what started the Big Bang. This is a big mystery.
The Big Bang is an idea about the history of the Universe, the history of space and time and matter (“stuff”) and energy. The Universe is about 13.8 billion years old and from observations we make using telescopes we can tell that the Universe was very small 13.8 billion years ago.
Observations also suggest that in the first fraction of a second, the Universe seemed to expand very quickly but then slow down. After a few hundred thousand years, the simplest type of atom formed: hydrogen. The hydrogen started to form stars and galaxies.
After billions of years the Earth (and us) formed from the atoms made inside stars – every atom in your body more complicated than hydrogen was made by a star at some point in the last 13.8 billion years. In all that time, the Universe has continued to expand. In fact, observations now tell us that the expansion of the Universe is getting faster.
The idea of the Big Bang agrees with all these observations. So scientists think the Big Bang is an idea that does a good job of describing the history of the Universe.
However, the idea is not perfect. We don’t know why the Universe expanded so quickly in the first second and then slowed down. We don’t know why the expansion of the Universe is speeding up now. We don’t know why we have a certain number of forces that control the Universe. And we don’t know what started the Big Bang!
Very large telescopes, like the Murchison Widefield Array can make observations that help us understand how the Universe evolved.
It took hundreds of years to build the idea of the Big Bang, and it may take a long time to improve it or find an idea that is better. Scientists have a lot of ideas about how the Big Bang started. But these ideas must agree with our observations of the Universe.
The future is very exciting for anyone who wants to help figure this out. The advanced technology we have means that we can build machines that smash particles (tiny little bits of stuff even smaller than an atom) together to show what happened right after the Big Bang. We can now build powerful new telescopes to observe the stars and galaxies in the Universe in a lot of detail. We will use these machines and telescopes to see which ideas about the Big Bang are right and which are wrong.
Sometimes new ideas take many years to be worked out. Sometimes new ideas pop into people’s heads very quickly. It is very exciting to have a new idea about the Universe. We will need lots of people who are good at puzzles to help us.
Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:
Please tell us your name, age, and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.
“Spreading out into space will completely change the future of humanity,” says Stephen Hawking. It “may be the only thing that saves us from ourselves. I am convinced that humans need to leave Earth”.
The world-famous physicist was talking at a recent science festival in Trondheim, Norway. And his keynote speech to the Starmus Festival about giving humanity a sense of purpose raises some very important questions about our views of positive futures.
For Hawking “a new and ambitious space programme would excite (young people), and stimulate interest in other areas, such as astrophysics and cosmology”. Humans have to leave Earth, he explained, due to an array of threats including asteroid strikes, resource depletion, overpopulation, deforestation, decimation of animal species, and the effects of human made climate change (particularly rising temperatures and melting ice caps).
Yet hearing such a viewpoint in response to the challenges we face leaves me cold. We cannot flee the apocalypse forever, leaving a chosen few to flourish on other planets; we need positive visions for humanity here on Earth.
I am not a physicist, I research and teach in a business school about how people and organisations go about taking action to address sustainability challenges, such as the global ecological threats mentioned by Hawking.
The concept of sustainability has been traced back to ideas that emerged in forestry about 300 years ago to sustain yields. The general implication of this expansive and slippery concept is that we need to work out ways to sustain both the social (including economic) and ecological processes that enable us to live in ways that we value.
Key questions are raised by Hawking’s speech and we can use these questions to briefly explore Hawking’s ideas about a future for humanity:
What is being sustained?
Hawking’s suggestion is that by establishing colonies on the moon or Mars we are helping to guarantee that some form of human life will continue beyond Earth being humanly habitable. What is being sustained is a protected bubble of a small selection of humans in artificially created Earth-styled environments somewhere in space.
How long is it being sustained?
Given his background in research into how the universe began – and will end – it is perhaps no surprise that in Hawking’s vision for humanity the time horizons are very long. His intention is for another million years of human life, with our space colonies enabling us to live even beyond the life of Earth itself.
In whose interest is what being sustained?
We can identify a range of core interests who would benefit from Hawking’s idea of humanity spreading out into space, including astrophysicists, astronauts, space agencies (science-related areas of work) which tend to be much more appealing to men and the members of the future space colonies.
But what about everyone not on the Ark?
The problem is that such a purpose or vision for humanity involves, and is relevant for, very limited groups of people. They will generally do certain types of jobs, and will be citizens of, or live in, those few countries that are putting serious money into space exploration. It’s easy enough to imagine a colony on Mars with the same sort of demographic makeup as a Silicon Valley tech giant. It’s much harder to imagine a colony populated by people with little financial wealth from less wealthy countries – the very people most affected by the environmental threats Hawking refers to.
I don’t have any particular objections to space travel itself. Interplanetary tourism doesn’t come cheap of course, and isn’t great for the carbon footprint, but if people want to leave planet Earth they are welcome to do so. My concern is that such visions are being presented as a benefit for all of human society.
After Hawking’s speech to the Starmus Festival, audience members put it to him that it would be better to spend our money on solving the problems of this planet. Hawking’s view is also one that is likely very enticing for a few, but alienating for many. This is partly because of the hopelessness of the apocalyptic vision for planet Earth, which is his starting point. This gloomy scenario can foster ambivalence by belittling what we can each do in the face of such enormous problems.
Hawking also puts too much emphasis on technology. The problem with sustainability visions that rely on tech advancements is they rarely factor in the complex task of sustaining conducive social-ecological relations. Yes, humans may eventually invent nuclear fusion, or a great way to suck carbon out of the atmosphere. But we’ll invent harmful things too, providing even more ways to trash the planet. Which sets of technologies are more significant will be a question of politics, not science.
It can be very difficult to face up to the social and ecological challenges that scientists have outlined and still develop some enthusiasm for positive “approach goals” instead of negative “avoidance goals”. New technologies are part of the positive picture, but too much tech talk is a distraction.
As we each develop our own view about what a positive future would look like, it’s clear that the real innovation must be in the ways we organise ourselves and live together on Earth – as there’s not much hope in only aiming for a life on Mars.
Scientists recently discovered the hottest planet ever found – with a surface temperature greater than some stars. As the hunt for planets outside our own solar system continues, we have discovered many other worlds with extreme features. And the ongoing exploration of our own solar system has revealed some pretty weird contenders, too. Here are seven of the most extreme.
How hot a planet gets depends primarily on how close it is to its host star – and on how hot that star burns. In our own solar system, Mercury is the closest planet to the sun at a mean distance of 57,910,000km. Temperatures on its dayside reach about 430°C, while the sun itself has a surface temperature of 5,500°C.
But stars more massive than the sun burn hotter. The star HD 195689 – also known as KELT-9 – is 2.5 times more massive than the sun and has a surface temperature of almost 10,000°C. Its planet, KELT-9b, is much closer to its host star than Mercury is to the sun.
Though we cannot measure the exact distance from afar, it circles its host star every 1.5 days (Mercury’s orbit takes 88 days). This results in a whopping 4300°C – which is hotter than many of the stars with a lower mass than our sun. The rocky planet Mercury would be a molten droplet of lava at this temperature. KELT-9b, however, is a Jupiter-type gas giant. It is shrivelling away as the molecules in its atmosphere are breaking down to their constituent atoms – and burning off.
At a temperature of just 50 degrees above absolute zero – -223°C – OGLE-2005-BLG-390Lb snatches the title of the coldest planet. At about 5.5 times the Earth’s mass it is likely to be a rocky planet too. Though not too distant from its host star at an orbit that would put it somewhere between Mars and Jupiter in our solar system, its host star is a low mass, cool star known as a red dwarf.
The planet is popularly referred to as Hoth in reference to an icy planet in the Star Wars franchise. Contrary to its fictional counterpart, however, it won’t be able to sustain much of an atmosphere (nor life, for that matter). This because most of its gases will be frozen solid – adding to the snow on the surface.
If a planet can be as hot as a star, what then makes the difference between stars and planets? Stars are so much more massive than planets that they are ignited by fusion processes as a result of the huge gravitational forces in their cores. Common stars like our sun burn by fusing hydrogen into helium. But there is a form of star called a brown dwarf, which are big enough to start some fusion processes but not large enough to sustain them. Planet DENIS-P J082303.1-491201 b with the equally unpronounceable alias 2MASS J08230313-4912012 b has 28.5 times the mass of Jupiter – making it the most massive planet listed in NASA’s exoplanet archive. It is so massive that it is debated whether it still is a planet (it would be a Jupiter-class gas giant) or whether it should actually be classified as a brown dwarf star. Ironically, its host star is a confirmed brown dwarf itself.
Just slightly larger than our moon and smaller than Mercury, Kepler-37b is the smallest exoplanet yet discovered. A rocky world, it is closer to its host star than Mercury is to the sun. That means the planet is too hot to support liquid water and hence life on its surface.
PSR B1620-26 b, at 12.7 billion years, is the oldest known planet. A gas giant 2.5 times the mass of Jupiter it has been seemingly around forever. Our universe at 13.8 billion years is only a billion years older.
PSR B1620-26 b has two host stars rotating around each other – and it has outseen the lives of both. These are a neutron star and a white dwarf, which are what is left when a star has burned all its fuel and exploded in a supernova. However, as it formed so early in the universe’s history, it probably doesn’t have enough of the heavy elements such as carbon and oxygen (which formed later) needed for life to evolve.
The planetary system V830 Tauri is only 2m years old. The host star has the same mass as our sun but twice the radius, which means it has not fully contracted into its final shape yet. The planet – a gas giant with three quarters the mass of Jupiter – is likewise probably still growing. That means it is acquiring more mass by frequently colliding with other planetary bodies like asteroids in its path – making it an unsafe place to be.
The worst weather
Because exoplanets are too far away for us to be able to observe any weather patterns we have to turn our eyes back to our solar system. If you have seen the giant swirling hurricanes photographed by the Juno spacecraft flying over Jupiter’s poles, the largest planet in our solar system is certainly a good contender. However, the title goes to Venus. A planet the same size of Earth, it is shrouded in clouds of sulfuric acid.
The atmosphere moves around the planet much faster than the planet rotates, with winds reaching hurricane speeds of 360km/h. Double-eyed cyclones are sustained above each pole. Its atmosphere is almost 100 times denser than Earth’s and made up of over 95% carbon dioxide. The resulting greenhouse effect creates hellish temperatures of at least 462°C on the surface, which is actually hotter than Mercury. Though bone-dry and hostile to life, the heat may explain why Venus has fewer volcanoes than Earth.
According to astronomers, the Milky Way is a bit of a loner.
A new study presented at the american astronomical society and two subsequent papers published in the Astrophysical Journal detail evidence that our region of the universe has fewer planets, stars, galaxies, and matter than other regions.
The void that our galaxy lives is known as KBC and it’s the largest void we’ve ever found. KBC (named after discoverers Keenan, Barger, and Cowie), is seven times larger than the average galactic void, measuring 1 billion light-years.
The idea that we live in this void is a handy explanation for problems with the Hubble Constant. The Hubble Constant is the unit of measurement used to describe the expansion of the universe. It’s called the ‘constant’ because the rate of expansion should be the same at every point in the universe, but it isn’t – which suggests that there are varying gravitational forces all over the universe.
“No matter what technique you use, you should get the same value for the expansion rate of the universe today. Fortunately, living in a void helps resolve this tension.”
Understanding our place in these voids is integral to learning about the large scale structure of our universe. Our universe is described as “Swiss cheese-like in the sense that it is composed of “normal matter” in the form of voids and filaments. The filaments are made up of superclusters and clusters of galaxies, which in turn are composed of stars, gas, dust and planets. Dark matter and dark energy, which cannot yet be directly observed, are believed to comprise approximately 95 percent of the contents of the universe.”
The latest findings show quite evidently that our galaxy lives in a much larger than average sized void which importantly highlights the differential rates at which our universe is expanding. It’s an important find that will aid astronomers in deciphering the structure of our cosmos.
How does a galaxy like our own Milky Way form? Until now there’s been a lot of inferring involved in answering that question.
The basic story is that gas collects toward the center of roughly spherical “halos” of matter. The gas then cools, condenses, fragments and eventually collapses to form stars. Generations of stars build up the galaxy and with it the production of heavy elements – such as carbon, oxygen and so on – that populate our periodic table and comprise our familiar physical world.
Astrophysicists like me have pieced together this picture thanks largely to theoretical research. We run numerical simulations on the world’s largest supercomputers to capture the processes that govern galaxy formation – gravitational collapse, heating, radiative cooling – at high fidelity.
To study many of these processes, we were largely restricted to this kind of theoretical inquiry because we didn’t have the technical capacity to observe them. But things have changed as we’ve witnessed the rise of what we consider the “Great Observatories”: NASA’s Hubble Space Telescope, the twin 10m Keck Telescopes on Manua Kea, Hawaii, and, most recently, the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile. With these facilities, astronomers have sought to test and refine the tenets of galaxy formation theory, especially the processes governing galaxy assembly and star formation.
The new data our group is publishing based on observations from ALMA are truly transformative relative to previous observations. They allow us to directly image the gas in nascent galaxies – something that was impossible before – and thereby test our fundamental predictions of galaxy formation.
The physical challenge
When we try to directly observe distant galaxies, the principal challenge is the very faint signal that reaches Earth from such great distances. The light from the two galaxies studied in our publication, for example, has traveled 12 billion light years to get here. This also means the light was emitted 12 billion years ago, when the universe was only 1.5 billion years old and galaxies were mere adolescents. And I’m especially interested in studying the gas that fuels star formation, which is particularly difficult to detect.
To address this challenge, starting in 1986 our group – led by the late Arthur M. Wolfe – relied on an indirect way to study distant galaxies. Rather than focusing on the galaxies themselves, we recorded the light from quasars that are even farther away from us. This allows us to probe gas in foreground galaxies.
Quasars are exceedingly bright objects that are powered by supermassive black holes. As a quasar’s light travels through the galactic gas we’re actually interested in, the atoms in the gas scatter a small portion of the light at well-defined wavelengths. It’s these so-called absorption signatures in the quasar’s spectrum that we focus on. The gas is imprinting its signature on the light we can collect with our telescopes.
We pass the light our telescope gathers through a spectrometer, an instrument that allows us to study the brightness as a function of wavelength. Then we can infer that there is in fact gas present between us and the quasar and we can quantitatively measure various properties of the gas.
Arthur used spectrometers at the primary observing suite of the University of California Observatories, first instruments on the Shane 3m telescope of the Lick Observatory and then, upon being commissioned, led research on the powerful Keck telescopes. These data provide estimates on the gas surface density, heavy element enrichment, molecular content and dynamical motions of the galaxy.
This observational experiment, however, is limited. It offers little information on the galaxy’s mass, size or star formation – all things that are fundamental to a galaxy’s makeup. It is critical that we measure these properties to understand the formation history of galaxies like our Milky Way.
In 2003, we reported that the then-future ALMA telescope would be a true game-changer by enabling us to directly image the gas within nascent galaxies. We would have to wait over a decade to begin while the telescope was built – so we had plenty of time to carefully identify the optimal targets and refine our observing strategies.
All the waiting and planning have now paid off. Arthur’s last Ph.D. student, Marcel Neeleman, just published our first results with ALMA and the data are spectacular. Here, in contrast to our previous work, we measure light from the gas in the galaxy itself, which reveals the size and shape of the star-forming regions. And what we saw was not what we expected.
ALMA collects light at wavelengths not visible to the human eye. We focused on two sources in our target galaxies: ionized carbon and warm dust, both of which surround the birthplace of new stars. We were able to create maps based on the light emitted by ionized carbon within a galaxy that we first detected in absorption, via our old technique.
Remarkably, the dense, star-forming gas of the galaxy is greatly offset from the hydrogen gas originally revealed by the quasar spectrum (by approximately 100,000 light years or 30 kiloparsecs). This distance shows that young galaxies are surrounded by a massive reservoir of un-ionized, neutral gas. We further suggest that the gas detected in absorption is likely to accrete back onto the galaxy and fuel future generations of stars.
The ALMA data also uniquely resolve the internal motions of the galaxy’s gas. Our analysis of the dynamics indicates the gas is configured in a large disk – similar to our Milky Way – and rotating with a speed of approximately 120 km/s. This speed is characteristic of what theory predicts for the progenitors of this sort of galaxy.
Lastly, we detected emission from “warm” dust in the galaxy. (Of course, warm is relative – in this case only about 30 degrees Celsius above absolute zero.) We believe the dust is heated by young massive stars; we estimate that the galaxy is forming stars at a rate of over 100 suns per year, a prodigious and precocious rate.
These data demonstrate the power and potential of ALMA to discover and dissect the progenitors of galaxies like our own. They will be invaluable to refine our understanding – in space and time – of the build-up of galaxies.
While many of us in the community held some reservations about ALMA (given its great cost), it is now clear to me the payoff will be extraordinary. ALMA research has already paid off in the discovery of protoplanetary disks from which planets form and unlocked hidden secrets of the process of star formation. And ALMA will continue to greatly advance our understanding of how galaxies like the Milky Way form.
Scientists have a love-hate relationship with anomalies. On the one hand, science is the attempt to bring rational order to the chaos of possible explanations, models, and interpretations for what we see when we look out into the great void that is space. Such is the case of another great void in the cosmic background radiation that pervades the entirety of the known universe. The background radiation, according to standard cosmological models, should be, for the most part, evenly distributed and consistent across space, but there is one blot or void in which there is less cosmic radiation than anywhere else, and it stands out because it is unlike any other spot in the known universe.
Many explanations have proliferated as a result of the anomaly, and one of the most intriguing of these is the possibility that the void represents a collision between two parallel universes. While the notion of parallel universes has occupied the imagination of both scientists and science fiction writers alike, it has often been met with skepticism in the scientific community. One of the major reasons for that is because a sound scientific theory must offer the possibility of being testable. With anomalies like the “Cold Spot” that dismissal may not be as damning as once thought.
However, there may be one catch to the “many worlds” interpretation that fundamentally changes how we perceive all those different worlds. Howard Wiseman, a Harvard physicist, says that our understanding of the “many worlds” interpretation is a bit off:
“The problem with the many worlds interpretation is that it’s fuzzy,” said Wiseman. “Simply put, we cannot count the number of worlds that exist at any point in time. This makes the whole notion very hard to reconcile with the claim that these worlds are real.”
“In our theory, all other worlds are as real as our world, and they’ve all been around since the beginning of time,” Wiseman said. “The only mystery is what particular world we occupy.”
This is an article from Curious Kids, a new series aimed at children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!
Does space go on forever? – Conrad, age 6, Sydney.
Space probably does go on forever, but the truth is we don’t know. Not yet anyway. That’s what makes this a great question, because science is all about finding answers to things we don’t know yet.
So, what do we know about space? We know it’s big, really big. It’s big enough to contain the Earth and all the other planets. It’s big enough to include the Sun and all the stars we see at night.
Not that long ago, people thought that when they looked up at the night sky, they were seeing all of space. That was until Edwin Hubble came along. He was an American astronomer and what he found out was so amazing that NASA named the famous Hubble Space Telescope after him.
Stars far, far away
Almost 100 years ago, Hubble, the astronomer, was looking at some small fuzzy patches of light hidden among all the stars we can see. No one was exactly sure what they were, but Hubble discovered that these patches of light were made of stars and even more importantly, they were a long way away.
With that one discovery, our idea of space exploded.
The stars we see in the night sky are part of the Milky Way Galaxy. That’s the galaxy we belong to.
The patches of light that Hubble was studying were other galaxies – each one filled with stars and planets and lots of other things too. Some galaxies are smaller than our Milky Way and others are larger.
Space was a whole lot bigger than anyone had ever imagined.
How to see forever?
Space is big, but does it go on forever? The problem is we can’t see forever. There’s a limit to how much space we can see, just like we can’t step outside our front door and see every city in Australia.
The part of space we can see is called the observable universe. It contains all the light we will ever be able to see (because when we look across space we are mostly looking for light).
The observable universe can even be measured. It is 93 billion light years from one side to the other. Now that’s a distance even astronomers find hard to think about. It’s like making about 300,000 laps of our Milky Way Galaxy, yet our Sun has only made 20 laps in its entire life. Or can you imagine lapping the Earth 20 million trillion times?
What’s more, the observable universe is centred on us because we are at the centre, looking out into space. An alien on another planet, in a far away galaxy, would have their own observable universe. You might want to think of each of us being inside our own bubble universe.
If our two bubbles overlapped, then the alien would see some of the same things we can see. But what about the places that are outside our bubble? Would the alien see emptiness at the edge of space?
No, probably not. What’s more likely is they would see a part of space that we will never ever be able to see.
In theory space goes on and on…
So why do scientists think that space goes on forever? It’s because of the shape of space. Our part of space, or the observable universe, has a special shape: it is flat.
That means if you and a friend each had your own rocket ship and you both took off and travelled in a straight line, forever and forever, you would never meet. In fact, you would always stay exactly the same distance apart, within the observable universe.
But this is a really special case. If space was shaped any other way, then lots of things could happen. Your two rockets, travelling in a straight line, might eventually cross paths or they might get really close but never meet or perhaps they’d go the other direction and drift away from each other.
But only flat space will keep the rockets exactly apart.
When one idea solves lots of problems, scientists call it a theory. It means we could be on the right track to finding an answer.
The theory says that space must be really, really big but we can only see a small part of it, and that part looks special and flat. It’s kind of like how Earth seems flat, unless you are an astronaut floating in space. Up there, you see so much more of the Earth that it’s possible to see how it curves away.
My bet is that space does go on forever. Maybe one day science will help tell us if that’s true.
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The discovery of massive galaxy that stopped making any new stars by the time the Universe was only 1.65 billion years old means we may have to rethink our theories on how galaxies formed.
The galaxy, known as ZF-COSMOS-20115, formed all of its stars (more than three times as many as our Milky Way has today) through an extreme starburst event.
But it stopped forming stars to become a “red and dead” galaxy not much more than a billion years after the Big Bang. Such galaxies are common in our Universe today but not expected to have existed at this ancient epoch. Galaxies turn red when they stop forming stars due to the resulting absence of hot, blue stars that have very short lifetimes.
It is an incredibly rare find that poses a new challenge to galaxy evolution models to accommodate the existence of such galaxies much earlier in the Universe.
An earlier discovery
To put this discovery in context, I’d like to give a short, personal history of research on early massive galaxies.
In 2004 I wrote an uncannily similar Nature paper about the existence of massive, old galaxies in the early Universe that were discovered in deep near-infrared surveys. At that time we were peering back across space to 3 billion years after the Big Bang.
These were a challenge for the models of galaxy formation that scientists were working with at the time, the start of a period where our pictures of how galaxies formed were rapidly being rewritten.
At the time, a picture of galaxies forming by lots of mergers in hierarchical assembly was in vogue. The problem was that this meant that today’s massive galaxies were in little bits billions of years ago.
But significant changes were made – driven in part by observations of the abundance of early massive galaxies, the observations of large gas-rich disk galaxies at these epochs and the discovery of “red nuggets” – extremely compact massive elliptical galaxies which stopped forming stars early on.
We moved to a picture where most galaxy growth and formation was driven by the formation of stars within the galaxy itself, from cosmic gas coming in to the galaxy.
This gas is fed into galaxies along the cosmic web by cold streams that are effective early on and allow us to grow massive galaxies more quickly in the computer modelling.
Many, many astronomers contributed to these developments and it was fun to play a minor role.
The new discovery
Back in 2013, one of our students, Caroline Straatman of Leiden University, discovered a population of pale red dots in the ZFOURGE survey.
These dots were bright in the near-infrared but very faint in the 35 other wavelength bands we observed. This peak suggested the presence of roughly 500 million year old stars but at a huge cosmic redshift.
In the local Universe this peak appears in blue light, so the redshift points to a time around 1.5 billion years after the Big Bang. The light suggested that no young stars were present, and the near-infrared brightness suggested these were massive objects (1011 solar masses).
To put this in context, our Milky Way has been growing continuously for 12 billion years but is 3-5 times less massive.
Even more remarkably, the galaxies looked like ellipticals and were almost point sources, even with high-resolution Hubble Space Telescope observations. They were less than 5,000 light years across. Extremely dense red nuggets at an earlier time than anyone had suspected.
Lines in the spectrum
In 2012 a powerful new near-infrared spectrograph was commissioned on the W M Keck telescopes in Hawaii. Last year we used it to get a two-night exposure on some of these objects.
We were amazed when we got a spectrum of the brightest (and most massive). They showed the distinct signature of Balmer absorption lines of stars around 500 million years old. Importantly there was no sign of current star-formation.
This galaxy was already massive and between 500 million and 1 billion years old.
It must have formed extremely fast, and then its star formation died quickly. This extreme behaviour could require significant rewriting of our pictures of galaxy formation in the first billion years of cosmic history.
Why? Well, we think galaxies form in the centres of halos of cold dark matter. Dark matter particles is not made of ordinary atoms, and particle physicists are still trying to detect these in the laboratory.
These halos can form very early and act as seeds for galaxy formation giving it a kick start. Without dark matter it would be difficult to form any galaxy.
The problem is at this early time there are barely enough massive dark matter halos to accommodate such massive galaxies. As a consequence in simulated Universes we don’t find this population of non-star forming galaxies so early, nor do we find the massive ancestors with extreme star-formation rates a billion years earlier.
So, do we need two recipes for galaxy formation where some form extremely quickly and the rest take 12 billion years?
Time will tell. The history of this field has shown that the theoretical community has a very strong record of postdiction (as opposed to prediction), and I expect a slew of papers will turn up in the next few weeks to explain this object!
Teasing of theorists aside, galaxy formation is a very difficult field to work in; the astrophysics are complex and it is very much driven by new observations which is why it is so much fun to work in.
Meanwhile our groups are pursuing the quest for massive galaxies to even earlier times. We have designed new filters to identify these and hope to start a new survey using the Gemini telescopes this year. Theorists, get your predictions in now.
Astrophysicists from the University of Birmingham have made significant progress in understanding a key mystery of gravitational wave astrophysics – they mystery of how two black holes can collide together and merge.
On September 14 2015 at 5:51 am the first confirmed detection of gravitational waves occurred. It made waves the scientific community as it confirmed a major theory of Albert Einstein’s from 1915. In which his Theory of General Relativity believed that gravity travels through the cosmos in ‘waves’.
The researchers said they detected gravitational waves coming from two black holes – extraordinarily dense objects whose existence also was foreseen by Einstein – that orbited one another, spiraled inward and smashed together. They said the waves were the product of a collision between two black holes 30 times as massive as the Sun, located 1.3 billion light years from Earth.
The scientific milestone, announced at a news conference in Washington, was achieved using a pair of giant laser detectors in the United States, located in Louisiana and Washington state, capping a long quest to confirm the existence of these waves.
The announcement was made in Washington by scientists from the California Institute of Technology, the Massachusetts Institute of Technology and the LIGO Scientific Collaboration.
From the University of Birmingham:
In order for the black holes to merge within the age of the Universe by emitting gravitational waves, they must start out very close together by astronomical standards, no more than about a fifth of the distance between the Earth and the Sun. However, massive stars, which are the progenitors of the black holes that LIGO has observed, expand to be much larger than this in the course of their evolution. The key challenge, then, is how to fit such large stars within a very small orbit. Several possible scenarios have been proposed to address this.
The Birmingham astrophysicists, joined by collaborator Professor Selma de Mink from the University of Amsterdam, have shown that all three observed events can be formed via the same formation channel: isolated binary evolution via a common-envelope phase.
A new paper, published in Nature Communications, goes into detail on locating the source of the gravitational anomaly. Using a newly developed toolkit named COMPAS (Compact Object Mergers: Population Astrophysics and Statistics), the team was able to comprehend the results from the event.
Senior author Professor Ilya Mandel spoke on the issue: “This work makes it possible to pursue a kind of ‘palaeontology’ for gravitational waves. A palaeontologist, who has never seen a living dinosaur, can figure out how the dinosaur looked and lived from its skeletal remains. In a similar way, we can analyse the mergers of black holes, and use these observations to figure out how those stars interacted during their brief but intense lives.”
— UniBirmingham News (@news_ub) April 5, 2017
— BIGWaves (@UoBIGWaves) March 21, 2017
— Class. Quantum Grav. (@CQGplus) March 30, 2017
It follows the publication this month of a new look at supernovae in our universe, which the researchers say give only a “marginal detection” of the acceleration of the universe.
This seems to be a big deal, because the 2011 Nobel Prize was awarded to the leaders of two teams that used supernovae to discover that the expansion of the universe is speeding up.
But never have I seen such a storm in a teacup. The new analysis, published in Scientific Reports, barely changes the original result, but puts a different (and in my opinion misleading) spin on it.
So why does this new paper claim that the detection of acceleration is “marginal”?
Well, it is marginal if you only use a single data set. After all, most big discoveries are initially marginal. If they were more obvious, they would have been discovered sooner.
The evidence, so far
The supernova data alone could, at only a slight stretch, be consistent with a universe that neither accelerates nor decelerates. This has been known since the original discovery, and is not under dispute.
But if you also add one more piece of information – for example, that matter exists – then there’s nothing marginal about it. New physics is clearly required.
In fact, if the universe didn’t accelerate or decelerate at all, which is an old proposal revisited in this new paper, new physics would still be required.
These days the important point is that if you take all of the supernova data and throw it in the bin, we still have ample evidence that the universe’s expansion accelerates.
The pattern of galaxies isn’t actually random, so we used this pattern to effectively lay grid paper over the universe and measure how its size changes with time.
Using this data alone shows the expanding universe is accelerating, and it is independent of any supernova information. The Nobel Prize was awarded only after this and many other observational techniques confirmed the supernova findings.
Something missing in the universe
Another example is the Cosmic Microwave Background (CMB), which is the leftover afterglow from the big bang and is one of the most precise observational measurements of the universe ever made. It shows that space is very close to flat.
Meanwhile observations of galaxies show that there simply isn’t enough matter or dark matter in the universe to make space flat. About 70% of the universe is missing.
So when observations of supernovae found that 70% of the universe is made up of dark energy, that solved the discrepancy. The supernovae were actually measured before the CMB, so essentially predicted that the CMB would measure a flat universe, a prediction that was confirmed beautifully.
So the evidence for some interesting new physics is now overwhelming.
I could go on, but everything we know so far supports the model in which the universe accelerates. For more detail see this review I wrote about the evidence for dark energy.
What is this ‘dark energy’?
One of the criticisms the new paper levels at standard cosmology is that the conclusion that the universe is accelerating is model dependent. That’s fair enough.
Usually cosmologists are careful to say that we are studying “dark energy”, which is the name we give to whatever is causing the apparent acceleration of the expansion of the universe. (Often we drop the “apparent” in that sentence, but it is there by implication.)
“Dark energy” is a blanket term we use to cover many possibilities, including that vacuum energy causes acceleration, or that we need a new theory of gravity, or even that we’ve misinterpreted general relativity and need a more sophisticated model.
The key feature that is not in dispute is that there is some significant new physics apparent in this data. There is something that goes beyond what we know about how the universe works – something that needs to be explained.
So let’s look at what the new paper actually did. To do so, let’s use an analogy.
Margins of measurement
Imagine you’re driving a car down a 60km/h limit road. You measure your speed to be 55km/h, but your odometer has some uncertainty in it. You take this into account, and are 99% sure that you are travelling between 51km/h and 59km/h.
Now your friend comes along and analyses your data slightly differently. She measures your speed to be 57km/h. Yes, it is slightly different from your measurement, but still consistent because your odometer is not that accurate.
But now your friend says: “Ha! You were only marginally below the speed limit. There’s every possibility that you were speeding!”
In other words, the answer didn’t change significantly, but the interpretation given in the paper takes the extreme of the allowed region and says “maybe the extreme is true”.
For those who like detail, the three standard deviation limit of the supernova data is big enough (just) to include a non-accelerating universe. But that is only if there is essentially no matter in the universe and you ignore all other measurements (see figure, below).
Improving the analysis
This new paper is trying to do something laudable. It is trying to improve the statistical analysis of the data (for comments on their analysis see).
As we get more and more data and the uncertainty on our measurement shrinks, it becomes more and more important to take into account every last detail.
In fact, with the Dark Energy Survey we have three people working full-time on testing and improving the statistical analysis we use to compare supernova data to theory.
We recognise the importance of improved statistical analysis because we’re soon going to have about 3,000 supernovae with which to measure the acceleration far more precisely than the original discoveries, which only had 52 supernovae between them. The sample that this new paper re-analyses contains 740 supernovae.
One final note about the conclusions in the paper. The authors suggest that a non-accelerating universe is worth considering. That’s fine. But you and I, the Earth, the Milky Way and all the other galaxies should gravitationally attract each other.
So a universe that just expands at a constant rate is actually just as strange as one that accelerates. You still have to explain why the expansion doesn’t slow down due to the gravity of everything it contains.
So even if the non-acceleration claim made in this paper is true, the explanation still requires new physics, and the search for the “dark energy” that explains it is just as important.
Healthy scepticism is vital in research. There is still much debate over what is causing the acceleration, and whether it is just an apparent acceleration that arises because our understanding of gravity is not yet complete.
Indeed that is what we as professional cosmologists spend our entire careers investigating. What this new paper and all the earlier papers agree on is that there is something that needs to be explained.
The supernova data show something genuinely weird is going on. The solution might be acceleration, or a new theory of gravity. Whatever it is, we will continue to search for it.
Dark matter is a mysterious substance composing most of the material universe, now widely thought to be some form of massive exotic particle. An intriguing alternative view is that dark matter is made of black holes formed during the first second of our universe’s existence, known as primordial black holes. Now a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, suggests that this interpretation aligns with our knowledge of cosmic infrared and X-ray background glows and may explain the unexpectedly high masses of merging black holes detected last year.
“This study is an effort to bring together a broad set of ideas and observations to test how well they fit, and the fit is surprisingly good,” said Alexander Kashlinsky, an astrophysicist at NASA Goddard. “If this is correct, then all galaxies, including our own, are embedded within a vast sphere of black holes each about 30 times the sun’s mass.”
In 2005, Kashlinsky led a team of astronomers using NASA’s Spitzer Space Telescope to explore the background glow of infrared light in one part of the sky. The researchers reported excessive patchiness in the glow and concluded it was likely caused by the aggregate light of the first sources to illuminate the universe more than 13 billion years ago. Follow-up studies confirmed that this cosmic infrared background (CIB) showed similar unexpected structure in other parts of the sky.
In 2013, another study compared how the cosmic X-ray background (CXB) detected by NASA’s Chandra X-ray Observatory compared to the CIB in the same area of the sky. The first stars emitted mainly optical and ultraviolet light, which today is stretched into the infrared by the expansion of space, so they should not contribute significantly to the CXB.
Yet the irregular glow of low-energy X-rays in the CXB matched the patchiness of the CIB quite well. The only object we know of that can be sufficiently luminous across this wide an energy range is a black hole. The research team concluded that primordial black holes must have been abundant among the earliest stars, making up at least about one out of every five of the sources contributing to the CIB.
The nature of dark matter remains one of the most important unresolved issues in astrophysics. Scientists currently favor theoretical models that explain dark matter as an exotic massive particle, but so far searches have failed to turn up evidence these hypothetical particles actually exist. NASA is currently investigating this issue as part of its Alpha Magnetic Spectrometer and Fermi Gamma-ray Space Telescope missions.
“These studies are providing increasingly sensitive results, slowly shrinking the box of parameters where dark matter particles can hide,” Kashlinsky said. “The failure to find them has led to renewed interest in studying how well primordial black holes — black holes formed in the universe’s first fraction of a second — could work as dark matter.”
Physicists have outlined several ways in which the hot, rapidly expanding universe could produce primordial black holes in the first thousandths of a second after the Big Bang. The older the universe is when these mechanisms take hold, the larger the black holes can be. And because the window for creating them lasts only a tiny fraction of the first second, scientists expect primordial black holes would exhibit a narrow range of masses.
On Sept. 14, gravitational waves produced by a pair of merging black holes 1.3 billion light-years away were captured by the Laser Interferometer Gravitational-Wave Observatory (LIGO) facilities in Hanford, Washington, and Livingston, Louisiana. This event marked the first-ever detection of gravitational waves as well as the first direct detection of black holes. The signal provided LIGO scientists with information about the masses of the individual black holes, which were 29 and 36 times the sun’s mass, plus or minus about four solar masses. These values were both unexpectedly large and surprisingly similar.
“Depending on the mechanism at work, primordial black holes could have properties very similar to what LIGO detected,” Kashlinsky explained. “If we assume this is the case, that LIGO caught a merger of black holes formed in the early universe, we can look at the consequences this has on our understanding of how the cosmos ultimately evolved.”
In his new paper, published May 24 in The Astrophysical Journal Letters, Kashlinsky analyzes what might have happened if dark matter consisted of a population of black holes similar to those detected by LIGO. The black holes distort the distribution of mass in the early universe, adding a small fluctuation that has consequences hundreds of millions of years later, when the first stars begin to form.
For much of the universe’s first 500 million years, normal matter remained too hot to coalesce into the first stars. Dark matter was unaffected by the high temperature because, whatever its nature, it primarily interacts through gravity. Aggregating by mutual attraction, dark matter first collapsed into clumps called minihaloes, which provided a gravitational seed enabling normal matter to accumulate. Hot gas collapsed toward the minihaloes, resulting in pockets of gas dense enough to further collapse on their own into the first stars. Kashlinsky shows that if black holes play the part of dark matter, this process occurs more rapidly and easily produces the lumpiness of the CIB detected in Spitzer data even if only a small fraction of minihaloes manage to produce stars.
As cosmic gas fell into the minihaloes, their constituent black holes would naturally capture some of it too. Matter falling toward a black hole heats up and ultimately produces X-rays. Together, infrared light from the first stars and X-rays from gas falling into dark matter black holes can account for the observed agreement between the patchiness of the CIB and the CXB.
Occasionally, some primordial black holes will pass close enough to be gravitationally captured into binary systems. The black holes in each of these binaries will, over eons, emit gravitational radiation, lose orbital energy and spiral inward, ultimately merging into a larger black hole like the event LIGO observed.
“Future LIGO observing runs will tell us much more about the universe’s population of black holes, and it won’t be long before we’ll know if the scenario I outline is either supported or ruled out,” Kashlinsky said.
Kashlinsky leads science team centered at Goddard that is participating in the European Space Agency’s Euclid mission, which is currently scheduled to launch in 2020. The project, named LIBRAE, will enable the observatory to probe source populations in the CIB with high precision and determine what portion was produced by black holes.
Originally published at NASA
An international team of scientists believe that new data supports the idea that our universe could be a hologram.
A study published in the Physical Review Letters seems to indicate that the argument for a holographic universe is just a strong as that of our standard cosmological model.
While it’s an astonishing claim, it doesn’t mean that our entire reality is a fabrication. Rather the holographic universe argument maintains that we need to rethink the way we envision our universe; specifically being that the holographic principle states that properties of three-dimensional universe’ could be encoded on a two dimensional surface.
“Imagine that everything you see, feel and hear in three dimensions (and your perception of time) in fact emanates from a flat two-dimensional field.The idea is similar to that of ordinary holograms where a three-dimensional image is encoded in a two-dimensional surface, such as in the hologram on a credit card. However, this time, the entire universe is encoded.”
– Professor Kostas Skenderis, University of Southampton
Research was tested against observations of the early universe made by the ESA’s Planck observatory. Some of the findings for the holographic theory universe did not add up, but for the most part the models satisfied the speculations.
“The structure of these deviations encodes the physics of the very early universe,” says Skenderis. “So then the question is, if you have a theory for the very early universe, can you predict the structure of the small deviations?”
“When we go into this concept of holography, it’s a new way of thinking about things. Even the scientists who worked on this for the past 20 years don’t have the right tools or the right language to describe what’s going on. It’s a new paradigm for a physical reality.”
“I would argue this is the simplest theory of the early universe. And so far, this is as simple as it gets. And it could help explain everything we see,” says Niayesh Afshordi, lead author of the paper. This idea, contrasted with Occam’s razor – a scientific and philosophic principle that maintains the simplest explanation is usually the correct one – paints a thought provoking picture. We may very well be living in a hologram.
High above the surface, Earth’s magnetic field constantly deflects incoming supersonic particles from the sun. These particles are disturbed in regions just outside of Earth’s magnetic field – and some are reflected into a turbulent region called the foreshock. New observations from NASA’s THEMIS – short for Time History of Events and Macroscale Interactions during Substorms – mission show that this turbulent region can accelerate electrons up to speeds approaching the speed of light. Such extremely fast particles have been observed in near-Earth space and many other places in the universe, but the mechanisms that accelerate them have not yet been concretely understood.
The new results provide the first steps towards an answer, while opening up more questions. The research finds electrons can be accelerated to extremely high speeds in a near-Earth region farther from Earth than previously thought possible – leading to new inquiries about what causes the acceleration. These findings may change the accepted theories on how electrons can be accelerated not only in shocks near Earth, but also throughout the universe. Having a better understanding of how particles are energized will help scientists and engineers better equip spacecraft and astronauts to deal with these particles, which can cause equipment to malfunction and affect space travelers.
“This affects pretty much every field that deals with high-energy particles, from studies of cosmic rays to solar flares and coronal mass ejections, which have the potential to damage satellites and affect astronauts on expeditions to Mars,” said Lynn Wilson, lead author of the paper on these results at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The results, published in Physical Review Letters, on Nov. 14, 2016, describe how such particles may get accelerated in specific regions just beyond Earth’s magnetic field. Typically, a particle streaming toward Earth first encounters a boundary region known as the bow shock, which forms a protective barrier between the solar wind, the continuous and varying stream of charged particles flowing from the sun, and Earth. The magnetic field in the bow shock slows the particles, causing most to be deflected away from Earth, though some are reflected back towards the sun. These reflected particles form a region of electrons and ions called the foreshock region.
Some of those particles in the foreshock region are highly energetic, fast moving electrons and ions. Historically, scientists have thought one way these particles get to such high energies is by bouncing back and forth across the bow shock, gaining a little extra energy from each collision. However, the new observations suggest the particles can also gain energy through electromagnetic activity in the foreshock region itself.
The observations that led to this discovery were taken from one of the THEMIS – short for Time History of Events and Macroscale Interactions during Substorms – mission satellites. The five THEMIS satellites circled Earth to study how the planet’s magnetosphere captured and released solar wind energy, in order to understand what initiates the geomagnetic substorms that cause aurora. The THEMIS orbits took the spacecraft across the foreshock boundary regions. The primary THEMIS mission concluded successfully in 2010 and now two of the satellites collect data in orbit around the moon.
Operating between the sun and Earth, the spacecraft found electrons accelerated to extremely high energies. The accelerated observations lasted less than a minute, but were much higher than the average energy of particles in the region, and much higher than can be explained by collisions alone. Simultaneous observations from the additional Heliophysics spacecraft, Wind and STEREO, showed no solar radio bursts or interplanetary shocks, so the high-energy electrons did not originate from solar activity.
“This is a puzzling case because we’re seeing energetic electrons where we don’t think they should be, and no model fits them,” said David Sibeck, co-author and THEMIS project scientist at NASA Goddard. “There is a gap in our knowledge, something basic is missing.”
The electrons also could not have originated from the bow shock, as had been previously thought. If the electrons were accelerated in the bow shock, they would have a preferred movement direction and location – in line with the magnetic field and moving away from the bow shock in a small, specific region. However, the observed electrons were moving in all directions, not just along magnetic field lines. Additionally, the bow shock can only produce energies at roughly one tenth of the observed electrons’ energies. Instead, the cause of the electrons’ acceleration was found to be within the foreshock region itself.
“It seems to suggest that incredibly small scale things are doing this because the large scale stuff can’t explain it,” Wilson said.
High-energy particles have been observed in the foreshock region for more than 50 years, but until now, no one had seen the high-energy electrons originate from within the foreshock region. This is partially due to the short timescale on which the electrons are accelerated, as previous observations had averaged over several minutes, which may have hidden any event. THEMIS gathers observations much more quickly, making it uniquely able to see the particles.
Next, the researchers intend to gather more observations from THEMIS to determine the specific mechanism behind the electrons’ acceleration.
Originally published at NASA
NASA has always been generous with their content. It hosts open-access image galleries, well written articles, full fledged television channels, and much more for usage on its sites. They’ve just added to the arsenal with a GIPHY and Pinterest page.
The GIPHY page contains some of the most mesmerizing images our universe holds – and we felt it necessary to provide an introduction.
Take a look at a few samples from NASA’s GIPHY below, or click here to see the entire gallery:
Last year astronomers recorded the brightest Supernova ever witnessed. New evidence shows that this event may not have been a Supernova at all.
The event known as ASASSN-15lh was twice as bright as the previous recorded record holder and was twenty times brighter than the entire light output of the Milky Way galaxy. Supernova of this category are brilliant displays of force that can be some of the most luminous objects in the universe.
Further research into the event casts a doubt on the findings of a supernova, and instead points to a Tidal Disruption Event (TDE). A TDE is the light emitted from a star when being torn apart by a massive black hole. An international team studied the event for over 10 months and published its findings in the journal Nature Astronomy.
“We’ve only been studying the optical flares of tidal disruptions for the last few years. ASASSN-15lh is similar in some ways to the other events we’ve been seeing, but is different in ways we didn’t expect. It turns out that these events, and the black holes that make them, are more diverse than we had previously imagined.” Says author Iair Arcavi.
Below you can see an animation of what may have occurred in this TDE:
When the event was first discovered by the All-Sky Automated Survey for Supernovae (ASASSN), astronomers didn’t initially agree with the findings of a Supernova. It was believed that stars at close to the center of our galaxy were not massive enough to produce such an explosion. This led researchers at the the Las Cumbres Observatory (LCO) to observe clues that pointed to a TDE, rather than a supernova.
“This is like discovering a new kind of dinosaur. Now that we have the right tools and know what to look for, we’re going to find more and get a better sense of the population. It is so exciting to have new ways of learning about black holes and stellar death!” Author Andy Howell.
Doomsday preppers have been thinking about various ways civilization could end for decades. They’re making preparations for apocalyptic endings ranging from asteroids hitting Earth to war breaking out. Even if you’re not a “prepper,” you may have questions about things in space that could end civilization. Let’s look at five of them.
1: Gamma Ray Burst
What could be the cause of a gamma-ray burst is when two stars collapse and merge. The result is what we know as the most powerful energy explosion throughout the universe. The energy this explosion produces is ten quadrillion times more than the sun.
The Earth detects the blasts at least once daily in galaxies that are millions of light-years from us. If these events were to happen any closer to our atmosphere, ten seconds of exposure to the intense flash of these gamma rays would completely destroy the ozone and atmosphere. Everything on the planet would become extinct.
CAPE CANAVERAL, Fla., (Reuters) – The ground-breaking detection of gravitational waves, ripples in space and time postulated by Albert Einstein 100 years ago, that was announced in February was no fluke. Scientists said on Wednesday that they have spotted them for a second time.
The researchers said they detected gravitational waves that washed over Earth after two distant black holes spiraled toward each other and merged into a single, larger abyss 1.4 billion years ago. That long-ago violent collision set off reverberations through spacetime, a fusion of the concepts of time and three-dimensional space.
These gravitational waves were observed by twin observatories in the United States late on Dec. 25, 2015 (early on Dec. 26 GMT). The detectors are located in Livingston, Louisiana, and Hanford, Washington.
The first detection of gravitational waves was made in September and announced on Feb. 11. It created a scientific sensation and was a benchmark in physics and astronomy, transforming a quirky implication of Einstein’s 1916 theory of gravity into the realm of observational astronomy.
The waves detected in September and December both were triggered by the merger of black holes, which are regions so dense with matter that not even photons of light can escape the gravitational sinkholes they produce in space.
The merging black holes that set space ringing in December were much smaller than the first pair, demonstrating the sensitivity of the recently upgraded Laser Interferometer Gravitational-wave Observatory, or LIGO, facilities.
“We are starting to get a glimpse of the kind of new astrophysical information that can only come from gravitational-wave detectors,” said Massachusetts Institute of Technology researcher David Shoemaker.
The black holes that triggered the newly detected gravitational waves were eight and 14 times more massive than the sun, respectively, before merging into a single, spinning black hole about 21 times more massive than the sun. The equivalent of one sun’s worth of mass was transformed into gravitational energy.
The Louisiana site detected the waves first and the Washington state detector picked up the signal 1.1 milliseconds later. Scientists can use the timing difference to calculate a rough idea of where the black holes merger occurred.
Scientists say the second detection confirms that pairs of black holes are relatively common.
“Now that we are able to detect gravitational waves, they are going to be a phenomenal source of new information about our galaxy and an entirely new channel for discoveries about the universe,” Pennsylvania State University astrophysicist Chad Hanna said.
The research, presented at the American Astronomical Society meeting in San Diego, will be published in the journal Physical Review Letters.
(Reporting by Irene Klotz; Editing by Will Dunham)
CAPE CANAVERAL, Fla. (Reuters) – Scientists for the first time have found a complex organic molecule in space that bears the same asymmetric structure as molecules that are key to life on Earth.
The researchers said on Tuesday they detected the complex organic molecule called propylene oxide in a giant cloud of gas and dust near the center of the Milky Way galaxy.
Akin to a pair of human hands, certain organic molecules including propylene oxide possess mirror-like versions of themselves, a chemical property called chirality. Scientists have long pondered why living things make use of only one version of certain molecules, such as the “right-handed” form of the sugar ribose, which is the backbone of DNA.
The discovery of propylene oxide in space boosts theories that chirality has cosmic origins.
“It is a pioneering leap forward in our understanding of how prebiotic molecules are made in the universe and the effects they may have on the origins of life,” chemist Brett McGuire of the National Radio Astronomy Observatory in Charlottesville, Virginia said in a statement.
These types of molecules, vital for biology, previously have been discovered in meteorites on Earth and in comets in our own solar system but never before in the enormous expanse of interstellar space.
The findings boost the notion that the chemical building blocks for life were delivered to Earth early in its history by celestial bodies like meteorites and comets that incorporated such molecules from space.
In May, researchers for the first time found the amino acid glycine, used by living organisms to make proteins, on a comet.
The scientists in the new study used radio telescopes to ferret out the chemical details of molecules in the distant, star-forming cloud of gas and dust. As molecules move around in the vacuum of space they emit telltale vibrations that appear as distinctive radio waves.
The complex signals tied to propylene oxide were not precise enough for the researchers to determine whether the molecules were orientated to the left or to the right.
Like a hand’s shadow, “it’s impossible to tell if the left or the right hand is casting the shadow,” said California Institute of Technology chemistry graduate student Brandon Carroll.
Future studies of how polarized light interacts with the molecules may reveal if one version of propylene oxide dominates in space, the researchers said.
The research was published in the journal Science. The scientists presented it on Tuesday at the American Astronomical Society meeting in San Diego.
(Reporting by Irene Klotz; Editing by Will Dunham)
CAPE CANAVERAL, Fla. (Reuters) – The universe is expanding faster than previously believed, a surprising discovery that could test part of Albert Einstein’s theory of relativity, a pillar of cosmology that has withstood challenges for a century.
The discovery that the universe is expanding 5 percent to 9 percent faster than predicted, announced in joint news releases by NASA and the European Space Agency, also stirs hypotheses about what fills the 95 percent of the cosmos that emits no light and no radiation, scientists said on Thursday.
“Maybe the universe is tricking us,” said Alex Filippenko, a University of California, Berkeley astronomer and co-author of an upcoming paper about the discovery.
The universe’s rate of expansion does not match predictions based on measurements of the remnant radiation left over from the Big Bang explosion that gave rise to the known universe 13.8 billion years ago.
One possibility for the discrepancy is that the universe has unknown subatomic particles, similar to neutrinos, that travel nearly as fast as the speed of light, which is about 186,000 miles (300,000 km) per second.
Another idea is that so-called “dark energy,” a mysterious, anti-gravity force discovered in 1998, may be shoving galaxies away from one another more powerfully than originally estimated.
“This may be an important clue to understanding those parts of the universe that make up 95 percent of everything and that don’t emit light, such as dark energy, dark matter and dark radiation,” physicist and lead author Adam Riess, with the Space Telescope Science Institute in Baltimore, Maryland, said in a statement.
Riess shared the 2011 Nobel Prize in Physics for the discovery that the expansion of the universe was speeding up.
The speedier universe also raises the possibility that Einstein’s general theory of relativity, which serves as the mathematical scaffolding for calculating how the basic building blocks of matter interact, is slightly wrong, NASA said.
Riess and colleagues made their discovery by building a better cosmic yardstick to calculate distances. They used the Hubble Space Telescope to measure a particular type of star, known as Cepheid variables, in 19 galaxies beyond our own Milky Way galaxy.
How fast these stars pulse is directly related to how bright they are, which in turn can be used to calculate their distances, much like a 100-watt light bulb appears dimmer the farther away it is.
The research will be published in an upcoming edition of The Astrophysical Journal.
(Reporting by Irene Klotz; editing by Daniel Trotta and Tom Brown)
CAPE CANAVERAL, Fla. (Reuters) – Scientists for the first time have directly detected key organic compounds in a comet, bolstering the notion that these celestial objects delivered such chemical building blocks for life long ago to Earth and throughout the solar system.
The European Space Agency’s Rosetta spacecraft made several detections of the amino acid glycine, used by living organisms to make proteins, in the cloud of gas and dust surrounding Comet 67P/Churyumov-Gerasimenko, scientists said on Friday.
Glycine previously was indirectly detected in samples returned to Earth in 2006 from another comet, Wild 2. But there were contamination issues with the samples, which landed in the Utah desert, that complicated the scientific analysis.
“Having found glycine in more than one comet shows that neither Wild 2 nor 67P are exceptions,” said Rosetta scientist Kathrin Altwegg of the University of Bern in Switzerland, who led the research published in the journal Science Advances.
The discovery implies that glycine is a common ingredient in regions of the universe where stars and planets have formed, Altwegg said.
“Amino acids are everywhere, and life could possibly also start in many places in the universe,” Altwegg added.
Altwegg and colleagues also found phosphorus, a key element in all living organisms, and other organic molecules in dust surrounding comet 67P. It was the first time phosphorus was found around a comet.Scientists have long debated the circumstances around the origin of life on Earth billions of years ago, including the hypothesis that comets and asteroids carrying organic molecules crashed into the oceans on the Earth early in its history.”Meteorites and now comets prove that Earth has been seeded with many critical biomolecules over its entire history,” said University of Washington astronomer Donald Brownlee, who led NASA’s Stardust comet sample return mission. Scientists plan to use Rosetta to look for other complex organic compounds around the same comet.
“You need more than amino acids to form a living cell,” Altwegg said. “It’s the multitude of molecules which make up the ingredients for life.” Rosetta is due to end its two-year mission at 67P by flying very close to the comet and then crash-land onto its surface this September.
67P is in an elliptical orbit that loops around the sun between the orbits of the planets Jupiter and Earth. The comet is heading back out toward Jupiter after reaching its closest approach to the sun last August.
(Reporting by Irene Klotz; Editing by Will Dunham)
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CAPE CANAVERAL, Fla. (Reuters) – Astronomers have discovered 1,284 more planets beyond our solar system, with nine possibly in orbits suitable for surface water that could bolster the prospects of supporting life, scientists said on Tuesday.
The announcement brings the total number of confirmed planets outside the solar system to 3,264. Called exoplanets, the bulk were detected by NASA’s Kepler space telescope, which searched for habitable planets like Earth.
The new planets were identified during Kepler’s four-year primary mission, which ended in 2013, and previously had been considered planet-candidates.
Scientists announcing the largest single finding of planets to date used a new analysis technique that applied statistical models to confirm the batch as planets, while ruling out scenarios that could falsely appear to be orbiting planets.
“We now know there could be more planets than stars,” Paul Hertz, NASA’s astrophysics division director, said in a news release. “This knowledge informs the future missions that are needed to take us ever closer to finding out whether we are alone in the universe.”
Of the new planets, nearly 550 could be rocky like Earth, NASA said. Nine planets are the right distance from a star to support temperatures at which water could pool. The discovery brings to 21 the total number of known planets with such conditions, which could permit life.
Kepler looked for slight changes in the amount of light coming from about 150,000 target stars. Some of the changes were caused by orbiting planets passing across, or transiting, the face of their host stars, relative to Kepler’s line of sight.
The phenomenon is identical to Monday’s transit of Mercury across the sun, as seen from Earth’s perspective.
The analysis technique, developed by Princeton University astronomer Tim Morton and colleagues, analyzed which changes in the amount of light are due to planets transiting and which are due to stars or other objects.
The team verified, with a more than 99 percent accuracy, that 1,284 candidates were indeed orbiting planets, Morton said.
The results suggest that more than 10 billion potentially habitable planets could exist throughout the galaxy, said Kepler lead scientist Natalie Batalha, with NASA’s Ames Research Center in Moffett Field, California. The nearest potentially habitable planet is about 11 light years from Earth.
“Astronomically speaking, that’s a very close neighbor,” she said.
(Reporting by Irene Klotz; Editing by Letitia Stein and James Dalgleish)
CAPE CANAVERAL, Fla. (Reuters) – Astronomers have found a first-of-its-kind tailless comet whose composition may offer clues into long-standing questions about the solar system’s formation and evolution, according to research published on Friday in the journal Science Advances.
The so-called “Manx” comet, named after a breed of cats without tails, was made of rocky materials that are normally found near Earth. Most comets are made of ice and other frozen compounds and were formed in solar system’s frigid far reaches.
Researchers believe the newly found comet was formed in the same region as Earth, then booted to the solar system’s backyard like a gravitational slingshot as planets jostled for position.
Scientists involved in the discovery now seek to learn how many more Manx comets exist, which could help to resolve debate over exactly how and when the solar system settled into its current configuration.
“Depending how many we find, we will know whether the giant planets danced across the solar system when they were young, or if they grew up quietly without moving much,” paper co-author Olivier Hainaut, an astronomer with the European Southern Observatory in Germany, said in a statement.
The new comet, known as C/2014 S3, was discovered in 2014 by the Panoramic Survey Telescope and Rapid Response System, or Pan-STARRS. This network of telescopes scours the night-time skies for fast-moving comets, asteroids and other celestial bodies.
Typically comets coming in from the same region as the Manx grow bright tails as they approach the sun, the result of ice vaporizing off their bodies and gleaming in reflected sunlight.
But C/2014 S3 was dark and virtually tailless when it was spotted about twice as far away from the sun as Earth.
Later analysis showed that instead of ices typically found on comets, the Manx comet contained materials similar to the rocky asteroids located in a belt between Mars and Jupiter.
And C/2014 S3 appeared pristine, an indication that it had been in the solar system’s deep freeze for a long time, said University of Hawaii astronomer Karen Meech, the lead author.
The discovery of additional Manx comets could help scientists to refine computer models used to simulate the solar system’s formation, Meech said.
(Reporting by Irene Klotz; editing by Letitia Stein and Diane Craft)
Astronomers using the Atacama Large Millimeter Array (ALMA) have captured an image of a dwarf galaxy made of mostly dark matter.
The image captured by ALMA shows distortions on light nearly 4 billion-light years away that are believed to be caused the gravity of an invisible dark matter galaxy.
The image as seen below shows faint red arcs surrounding a galaxy (shown in blue). The distortions are believed to be caused by an immense amount of dark matter. This matter does not emit or absorb light, it rather causes a gravitational lensing effect that produces what you can see in ALMA’s latest image.
“We can find these invisible objects in the same way that you can see rain droplets on a window. You know they are there because they distort the image of the background objects,” explains Yashar Hezaveh a Stanford University astronomer.
This research has a deep significance for astronomers; it means that we may have not been seeing a large majority of cosmic objects that are made up of mostly dark matter.
Astronomers and researches have been noticing gravitational distortions for decades and have been chalking them up to discrepancy. It’s possible we’re just scratching the surface of hidden objects in our universe.
Earlier this year we wrote about The Smith Cloud. The Smith Cloud is a ball of gas travelling at over 310 kilometers per second on a crash course for the Milky Way.
NASA’s Jet Propulsion laboratory has put together the following diagram to illustrate the course of trajectory over the next 30 million years:
Astronomers have found a supermassive black hole weighing in at 17 billion suns in a sparsely populated area of the universe.
The observations were made by the Hubble Space Telescope and the Gemini Telescope in Hawaii. This find, located in the center of a galaxy, may indicate that these supermassive black holes are far more common than previously thought.
The biggest supermassive black hole recorded to date has a mass of 21 billion suns and resides in the Coma galaxy cluster which contains over 1,000 galaxies. Earlier this year, astronomers suggested that super massive black holes may be able to reach a mass of up to 50 billion suns.
“The newly discovered supersized black hole resides in the center of a massive elliptical galaxy, NGC 1600, located in a cosmic backwater, a small grouping of 20 or so galaxies,” says lead discoverer Chung-Pei Ma, a University of California-Berkeley astronomer. “There are quite a few galaxies the size of NGC 1600 that reside in average-size galaxy groups,” Ma said. “We estimate that these smaller groups are about 50 times more abundant than spectacular galaxy clusters like the Coma cluster. So the question now is, ‘Is this the tip of an iceberg?’ Maybe there are more monster black holes out there that don’t live in a skyscraper in Manhattan, but in a tall building somewhere in the Midwestern plains.”
A new paper from David Kipping, an astronomer at Columbia University believes it could.
In this paper David Kipping goes on to explain how a 22W laser could disrupt measurements of the Earth’s orbit around the sun, thus deceiving any potential harmful onlookers.
Kipping and his graduate student Alex Teachey, conclude that it would be remarkably easy to “wipe out” Earth’s signal, or at the least distort it. All you need to do is disrupt the “transit method” most commonly used to identify objects in orbit around stars. The transit method is how we identify most planets today, by looking for dips within the light signals of stars – when believed objects pass by.
“To make it look like the planet is not there at all, you’ve got to get rid of that dip. You’ve got to fill in the missing starlight,” Teachey tells in a video.
Planets can still be detected in other ways, such as the gravitational influence on a star – however the idea behind this technology is that it would act as a deterrent to arousing suspicion, thus hindering the possibility of conducting such gravitational experiments.
The idea of cloaking ourselves from aliens could work. However, it needs one specific caveat to make any sense – a universe in which we suspect extra terrestrial life exists, and peering into our daily lives. While that may be entirely true, it’s likely that this theory remains just a fun possibility for astronomers.
Astronomers have located a superheated region of dust and gas emitting jets seventy times hotter than was previously thought possible.
Telescope RadioAstron was aimed at quasar 3C 273, one of the most luminous known quasars over 2.4 billion light-years away, and with a brilliance 4 trillion times that of the sun. It’s located in the center of galaxy, so it has been extremely hard to study up until now. RadioAstron is special from other telescopes in that it operates at radio wavelengths – and it’s this difference that is unlocking new cosmic discoveries.
A model suggests that these jets have the potential to reach up to 100 billion degrees kelvin, but the team at RadioAstron have found different, hotter evidence. Something this bright is bound to be very, very hot says Dr. Yuri Kovalev, a RadioAstron scientist.
“We measure the effective temperature of the quasar core to be hotter than 10 trillion degrees! This result is very challenging to explain with our current understanding of how relativistic jets of quasars radiate.”
RadioAstron has been beaming back data since 2011 and is expected to bring us new and exciting discoveries in the future. The telescope has an immense range of 171,000 kilometers (106,000 miles) which has astronomers pining for the next unseen views of the cosmos.
Hunting for exoplanets, scientists have found one of the most fascinating planets to date. A sinister “Super-Earth” that is half molten magma, and half perpetual night.
The planet is named 55 Cancri e. It’s 41 light-years from our planet and was initially discovered in 2004, classified as the first Super-Earth, a planet with a mass larger than ours but smaller than Neptune. Another characteristic of Super-Earths is that they orbit around a main sequence star.
55 Cancri e is located so close to it’s star that it’s orbit speeds by in just 18 years. A rough calculation shows that in one earth year, it orbits it’s host star 487 times. Cancri has an atmosphere that reaches 2,000°C (3,600°F) and is filled with poisonous gases such as cyanide. It goes without saying that you do not want to live here.
What seperates the new research from the initial find in 2004 is new imaging data from NASA’s Spitzer Space Telescope that detects infrared emissions. Thanks to Spitzer, astrophysicist Brice-Olivier Demory was able to tell the story of a world with two drastically different hemispheres.
Thanks in part to the gravity of it’s star, the planet is tidally locked and only one hemisphere faces the star at all times. This is the same reason we only see one side of our moon from Earth. The new data showed that the side facing it’s star reaches up to 2,500°C (4,530°F) and is in a constant state of molten flux. The other half is cast in perpetual night at a cooler, but still remarkable, temperature of 1,100°C (2,010°F).
The cold side is covered with solidified lava, whereas the hotter side is dominated by a frightening magma ocean. And strangely so, the planet is much hotter than it is supposed to be. Data from Spitzer shows that it is not receiving enough heat from it’s host star to reach such temperatures, thus scientists believed that there are unknown forces at work at the heart of the planet.
“We still don’t know exactly what this planet is made of – it’s still a riddle,” says Demory. “These results are like adding another brick to the wall, but the exact nature of this planet is still not completely understood.”
A study of Jupiter’s atmosphere has revealed aurorae that outshine those on Earth by a factor of several hundred times.
Aurora are caused by interactions with solar wind and a planet’s magnetic field. When charged particles from the sun disturb magnetic fields the particles interact with atoms and molecules in a planet’s pole to produce amazing light shows.
When this happens on Earth it’s known as the Aurora Borealis, or Australis – and it’s quite a sight. Earth is relatively close to the Sun which allows for aurorae to form around it’s magnetic field, but even though Jupiter is five times the distance it can produce the same effect – thanks in part to a magnetic field that puts the Earth’s to shame. Because of this large field, Jupiter can produce aurorae more frequently than Earth.
“There’s a constant power struggle between the solar wind and Jupiter’s magnetosphere,” says William Dunn, of the University College London. “We want to understand this interaction and what effect it has on the planet. By studying how the aurora changes, we can discover more about the region of space controlled by Jupiter’s magnetic field, and if or how this is influenced by the Sun. Understanding this relationship is important for the countless magnetic objects across the galaxy, including exoplanets, brown dwarfs and neutron stars.”
Dunn describes the observations of a coronal mass ejection (or CME) that reached Jupiter in 2011 in the journal of Space Physics. In this he speaks on the Juno’s spacecraft mission, which will arrive at Jupiter in July. One of Juno’s goals will be to study the magnetosphere of Jupiter for this very phenomena (We’re hoping we’ll get some amazing pictures).
The observations also show that X-Ray emissions are largely accelerated by Jupiter’s magnetic field. These aurorae are so powerful that they produce X-Ray emissions visible to Chandra’s X-Ray telescope here on Earth.
A team of researchers using the NASA/ESA Hubble Space Telescope have found nine massive stars located 17,000 light-years away from Earth.
The cluster is named R136, and lives in the gorgeous Tarantula Nebula. These stars are estimated to have masses over 100 times that of the sun, making this find one of the largest samples of large stars in one region known to date. The largest known star is the universe is still R136a1, which is larger than 250 solar masses.
“Together these nine stars outshine the Sun by a factor of 30 million,” according to the European Space Agency who found the stars using Hubble’s Wide Field Camera 3 (WFC3) and the Space Telescope Imaging Spectrograph (STIS).
Hubble also found other slumbering monsters in star cluster R136, finding at least a dozen stars with 50 solar masses or more.
“Because they are so massive, they are all close to their so-called Eddington limit, which is the maximum luminosity a star can have before it rips itself apart; and so they’ve got really powerful outflows. They are shedding mass at a fair rate of knots,”Paul Crowther of the University of Sheffield tells BBC.
Along with the find come new questions about the formation of super-massive stars. When the first stars of these type were found in 2010, scientists were puzzled to learn that stars could form this large. Armed with information that they can get even bigger, in such large numbers – brings about new questions for researchers.
“There have been suggestions that these monsters result from the merger of less extreme stars in close binary systems. From what we know about the frequency of massive mergers, this scenario can’t account for all the really massive stars that we see in R136, so it would appear that such stars can originate from the star formation process,” says Crowther.
The formation of a star is caused by dense clouds of collapsed gas, but there are many questions around the earlier stages of their life cycle.
Yet recently Japanese researchers have found new evidence that will help scientists understand what’s going on during a star’s infancy.
With the help of the Atacama Large Millimeter/submillimeter Array (ALMA) the team was able to see the formation of the disk around a young star named TMC-1A. This star is 0.68 times the mass of our Sun and is 450 light years from Earth. The star is going through an important phase in it’s life; building up a proto-planetry disk which will eventually lead to the formation of planets.
This find unlocks a new understanding of stellar of formation as written in the Astrophysical Journal.
“The disks around young stars are the places where planets will be formed,” said lead author Yusuke Aso in a statement. “To understand the formation mechanism of a disk, we need to differentiate the disk from the outer envelope precisely and pinpoint the location of its boundary.”
ALMA helped the team identify the active areas around the star that showed the planetary disk. The disk extends 13 billion kilometers (8 billion miles) from the star and rotates at a tremendous speed. Because of ALMA’s sensitivity, this is the first time we have seen this phenomena with such accuracy.
“We expect that as the baby star grows, the boundary between the disk and the infall region moves outward. We are sure that future ALMA observations will reveal such evolution.”
This is the BOSS. It is a wall of galaxies 1 billion light years across, and the largest thing ever identified in the cosmos.
Picturing the scale of our cosmos has long been unfathomable for the human mind, so it may be safe to say that describing the BOSS is incredibly difficult. Known as the BOSS of Great Wall, this supercluster of galaxies is over 1 billion light years across and the largest thing that astronomers have come by to date.
BOSS is named after the Baryon Oscillation Spectroscopic Survey, an effort to map galaxies in the early universe. This massive superstructure is made up of four superclusters that are connected by huge filaments of hot gas, dark matter, and empty space – as reported by New Scientist.
The BOSS is roughly 5.5 billion lightyears away and has an estimated mass 10,000 times that of our Milky Way. The Sloan Great Wall was previously thought to be the largest known object in the cosmos, but the Great Wall dwarfs this find.
Finding these superstructures are incredibly important to astronomers; they help to model the big bang and the shape of our universe. As we continue to unlock the hidden secrets of our cosmos, it is possible we find larger objects.
The BOSS Great Wall is a galaxy wall, a subtype of galaxy filaments, that was discovered early 2016. It is one of the largest superstructures in the observable universe. It contains perhaps 10 000 times the mass of the Milky Way. It is 1 billion light years across, and contains 830 visible galaxies, as well as many others that are invisible (dark galaxies). It contains five times the density compared to the standard cosmological density of the universe. Its redshift is about z=0.47 (z times Hubble length ≈ 6800 million light years). Although this structure may look grand in size to us, we may not be able to call it one solid structure just yet. This part of the sky has five times as many galaxies as an average space in the sky, but we know the universe is still expanding. This brings about the question of whether they are all moving together or are slowly separating as the universe expands.
It was discovered using the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey, hence its name, by H. Lietzen, E. Tempel, L. J. Liivamägi, A. Montero-Dorta, M. Einasto, A. Streblyanska, C. Maraston, J. A. Rubiño-Martín and E. Saar.
This article references the Cornell study on the Discovery of a massive supercluster system.
CAPE CANAVERAL, Fla. (Reuters) – Astronomers said on Thursday they had discovered a galaxy that formed just 400 million years after the Big Bang explosion, the most distant galaxy found to date.
Located a record 13.4 billion light-years from Earth in the direction of the constellation Ursa Major, the galaxy, named GN-z11, was first spotted two years ago in a Hubble Space Telescope deep-sky visible light survey.
At the time, astronomers knew they were seeing something very far away, possibly as distant as 13.2 billion light-years from Earth.
Follow-up observations with an instrument on Hubble that splits light into its component wavelengths revealed that GN-z11 was farther away than initially believed, setting back the galaxy-formation clock by another 200 million years.
Being able to use Hubble to peg the galaxy’s distance was a surprise, said astronomers who will publish their research in next week’s issue of The Astrophysical Journal.
“We’ve taken a major step back in time, beyond what we’d ever expected to be able to do with Hubble,” Yale University astronomer Pascal Oesch said in a statement.
The key to the discovery was precisely measuring the shift of the galaxy’s light into longer, redder wavelengths, which directly corresponds to how far the photons had traveled before reaching Hubble’s eye.
The phenomenon is similar to the sound of a train whistle shifting pitch as it recedes into the distance.
Though small by modern galaxy standards, GN-z11 is huge considering it formed at a time when the universe was only 3 percent of its present age, said astronomer Garth Illingworth with the University of California, Santa Cruz.
“We’re seeing this galaxy in its infancy,” Illingworth said. “It’s amazing that a galaxy so massive existed only 200 million to 300 million years after the very first stars started to form.”
GN-z11 contains about 1 billion times the mass of the sun. The galaxy is about 25 times smaller than the Milky Way, though it is pumping out new stars 20 times faster than the present Milky Way.
Astronomers said they expected the new distance record to stand until Hubble’s successor, the James Webb Space Telescope, is launched in 2018.
(Reporting by Irene Klotz; Editing by Ian Simpson and Sandra Maler)
Exploding stars are a key point of focus for scientists who hope to understand the lifecycle of stellar bodies and how they interact with their surroundings.
Supernovae are undoubtably one of the cosmos’ greatest actors. They put on spectacular shows unrivalled by anything we could fathom; some supernova being 2nd only to the big bang in the amount of energy produced by one single event.
But now, researchers at the NASA Chandra X-ray Observatory have been studying one particular explosion that they believe may provide clues to the dynamics of other, much larger eruptions. These explosions are called “classical nova”, and they’re the smaller cousins of Supernovae.
In 1901 a star suddenly appeared in the night sky as one of the brightest ever seen, for just a few days. Before it faded away, astronomers had deduced that this was infact the first ever witnessed classical nova – and the object became a rapid sensation in the astronomical world. This star was known as GK Persei.
Today, we are still studying GK Persei, and the team at Chandra has found some interesting data that may help to understand the evolution of stars. The nova’s debris is expanding at a speed of 700,000 miles per hour which translates to the blast wave moving about 90 billion miles.
GK Persei is a white dwarf star that pulled in material from orbiting companion stars. When enough material accumulated on the surface of the star (in the form of hydrogen gas) nuclear fusion takes place and culminates into a hydrogen-bomb like explosion on a stellar scale. The outer layers of GK Persei were blown away, which produced the nova outburst visible here on Earth.
Building The Case
Observing GK Persei from 2000 to 2013 gave astronomers at Chandra an opportunity to build a 13 year baseline on the event and collect a significant amount of data to notice important differences in x-ray emissions and life cycles. What was so important about this research was the understanding of the nova’s dynamic; while a nova is a much smaller version of a supernova, it is still expected to be so bright that it will outshine all stars in the galaxy it is found in. Additionally, novas are very important for cosmic evolution as they blast iron, calcium, and oxygen into space – which helps with the formation of new stars and planets.
One discovery in the search shows that nova remnants can provide extremely important clues to the environment of the solar system at the time of the explosion. By measuring the changes in density before and after the explosion, scientists can determine how the blast wave passes through the cosmos, which ultimately paints a picture of the density of its current and previous region of space.