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Black holes born soon after Big Bang

Illustration of supermassive black hole

Astronomers have found the first direct evidence that black holes existed when the Universe was less than a tenth of its present age. (Artist's impression)

USING THE MOST SENSITIVE X-ray image ever taken, University of Hawaii astronomer Ezequiel Treister and colleagues have found the first direct evidence that black holes existed when the Universe was less than a tenth of its present age.

Between 30 and 100 percent of the 200 distant galaxies they observed contained a central black hole that was voraciously consuming the gas and stars that surrounded them.

This discovery was made with NASA’s orbiting Chandra X-ray Observatory.

“Black holes are objects whose gravity is so strong that not even light can escape from them. Until now, we had no idea what the black holes in these early galaxies were doing—or if they even existed,” said Treister, lead author of the study that appears in this week’s Nature. “Now we know they are there and they are growing like gangbusters.”

“It appears we’ve found a whole new population of baby black holes,” said co-author Kevin Schawinski of Yale University. “We think these babies will grow by a factor of about a hundred or a thousand, eventually becoming like the giant black holes we see today almost 13 billion years later.”

A population of very young black holes in the early Universe had been predicted, but not yet observed. Detailed calculations show that the total amount of black hole growth observed by this team is about a hundred times higher than recent estimates.

Because these very young black holes are nearly all enshrouded in thick clouds of gas and dust, optical telescopes frequently cannot detect them. However, the high energies of X-ray light can penetrate these veils, allowing the black holes inside to be studied.

Adapted from information issued by the University of Hawaii.

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Dark energy dilemma

PHYSICISTS CAN’T SEE IT and don’t know much about what it is, but they think dark energy makes up 70 percent of the universe. In this video, Professor Saul Perlmutter, one of the world’s leading scientists trying to understand dark energy, explains the role it plays in causing our universe to expand.

Adapted from information issued by Lawrence Berkeley National Laboratory / KQEDondemand.

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The outer limits

Hubble image of distant galaxy

Earlier this year, the Hubble Space Telescope spotted what could be the farthest and one of the very earliest galaxies ever seen in the universe so far. This is the deepest infrared image taken of the universe (deeper even than the Hubble Deep Field; see image below). Based on the galaxy's colour, astronomers believe it is a staggering 13.2 billion light-years away.

HOW FAR CAN WE SEE into the cosmos? And what lies beyond what we can see? Will we ever know what exists beyond the ‘edge of space’?

These questions were posed recently by SpaceInfo readers in response to our story on what astronomers will see one trillion years from now.

They’re very interesting questions indeed. The answers require a bit of thought, and especially they require someone who knows what they’re talking about and can provide them in an understandable manner.

Dr Tamara Davis

Dr Tamara Davis

Introducing Dr Tamara Davis, a cosmologist and Research Fellow in the Physics Department at the University of Queensland. Tamara is involved in some of the most exciting cosmological research going at the moment, and her achievements were recognised a couple of years ago when she was honoured with the 2009 L’Oréal Women in Science Award.

We’re grateful to Tamara for taking the time to give us the following brief explanation of how far we can see, how far we might be able to see in the future, and why there are some things we’ll never see.

Our cosmic Horizons

by Dr Tamara Davis, University of Queensland

SpaceInfo readers have asked about what lies beyond the reach of our view of the cosmos. This is a great question, and I hope the following explanation will help everyone to understand the situation.

There are actually two types of ‘cosmic horizon’. There’s a limit to how far we can see right now, and a different limit to how far we’ll be able to see in the far future.

The limit to how far we can see right now is called our “particle horizon” because it is the distance to the most far-away “particle” (eg. galaxy) that we can currently see.

The particle horizon arises because light has been able to travel only a finite distance since the Big Bang. If we had been around to shine a light from our position at the time of the Big Bang, then the distance that light could have travelled by now is the distance to our particle horizon.

This kind of horizon is getting bigger as time goes on (as light has more time to travel), and we’re continually able to see things further and further away (and further and further back in time).

Practically speaking, we can’t actually see all the way to our theoretical particle horizon because to do so we’d have to see light that was emitted right at the moment of the Big Bang. The universe was so dense back then that light couldn’t travel very far before getting scattered. It was unable to ‘break out’ from the dense cosmic ‘soup’.

In practical terms the most distant thing we can see is what cosmologists call the “last scattering surface”. This was the state of play about 100,000 years after the Big Bang, when the universe’s density dropped to the point that light could break out and travel relatively unimpeded.

These days we perceive that light as a uniform glow of microwave radiation from all directions, known as the cosmic microwave background. Some of the static picked up by old analogue TVs came from this radiation … so, funnily enough, when you saw fuzz on your TV screen you were actually detecting light from our effective particle horizon!

Hubble Deep Field

The Hubble Deep Field is one of the iconic images of space, showing us galaxies into the far distant universe. And the further away a galaxy is, the further back in time we're seeing it.

Edge of the great unknown

The other type of horizon, probably more relevant to the discussion in the original article, is our “event horizon”, which is the limit to how far we will be able to see in the infinite future.

If we were to shine a light outwards from our position now, then the distance it can travel in the future is our event horizon.

Now, you might think that, unless the cosmos were to somehow end, a light beam could travel an infinite distance into an infinite future. But in a universe whose rate of expansion is accelerating (like ours) that isn’t true, so there’s a limit to how far we will be able to see, even given infinite time.

This is because there are distant parts of the universe expanding away from us faster than the speed of light… the only way light from galaxies in the most distant reaches of the universe can reach us is if the universe’s expansion slows down.

It’s a bit like a swimmer caught in a rip, trying to swim back to shore…she can’t swim faster than the rip, so she’ll never make it. Unless the rip slows down she hasn’t got a chance.

But our universe is not slowing down, the expansion is actually speeding up, so light from some distant galaxies will forever be out of view.

This limit is called our “event horizon” because it separates events we will be able to see from events we will never be able to see.

The event horizon is actually a more stringent limit than the particle horizon, because not only do you have to ask whether you can see the particle, but also if you can see it for its entire life.

Many galaxies that we can currently see are actually, by now, well beyond our event horizon—because although we can see them as they were in the past, we will never be able to see them as they are today.

Our current event horizon is at a redshift of 1.8…that’s about 5 giga-parsecs away. (A giga-parsec is one billion parsecs, with a parsec being 3.26 light-years.)

You might have seen the Hubble Deep Field (see image above)—one of the ‘deepest,’ most detailed photos of the universe ever taken. The most distant galaxy in that image is beyond a redshift of 6 (more than 8 giga-parsecs away).

That means that a huge number of the galaxies we can see in that image are now actually beyond our event horizon. The Hubble Deep Field shows us a snapshot of them as they were in the past, but we’ll never be able to communicate with them.

More information

For more information about this subject, and for some scientific diagrams of how far we can see in the universe, you can download a fascinating PDF-format article by Tamara from http://www.physics.uq.edu.au/download/tamarad/astro/scienceimages/Spacetime_diagrams.pdf

She’s also written another great article that helps straighten out this wide topic, “Misconceptions about the Big Bang” (Scientific American, March 2005). And for even more information you can visit her website at http://www.physics.uq.edu.au/download/tamarad/astro/index.html

Distant galaxy image courtesy NASA, ESA, Garth Illingworth (UC Santa Cruz), Rychard Bouwens (UC Santa Cruz and Leiden University) and the HUDF09 Team / A. Feild (STScI). HDF image courtesy R. Williams (STScI), the Hubble Deep Field Team and NASA. Tamara Davis image courtesy timothyburgess.net / Science in Public.

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Astronomy 1 trillion years from now

Artist’s conception of the cosmic view a trillion years from now.

A trillion years from now, the sky will look very different. Will astronomers still be able to work out that the Big Bang happened?

ONE TRILLION YEARS FROM NOW, alien astronomers in our galaxy will have a difficult time figuring out how the universe began. They won’t have the evidence that we enjoy today.

Edwin Hubble made the first observations in support of the Big Bang model. He showed that galaxies are rushing away from each other due to the universe’s expansion.

More recently, astronomers discovered a pervasive afterglow from the Big Bang, known as the cosmic microwave background, left over from the universe’s white-hot beginning.

In a trillion years, when the universe is 100 times older than it is now, alien astronomers will have a very different view. The Milky Way will have merged with the Andromeda Galaxy to form the ‘Milkomeda Galaxy’. Many of its stars, including our Sun, will have burned out.

And the universe’s ever-accelerating expansion will send all other galaxies rushing beyond our “cosmic horizon,” sending them forever out of view.

The same expansion will cause the cosmic microwave background (CMB) to fade out, stretching the wavelength of CMB photons to become longer than the visible universe.

The universe will become dark and dull.

Artist's impression of a hypervelocity star.

Future astronomers will study hypervelocity stars to deduce the laws of the cosmos.

Shooting stars

Without the clues of the CMB and distant, receding galaxies, how will these far-future astronomers know the Big Bang happened?

According to Harvard theorist Avi Loeb, clever astronomers in the year 1 trillion CE could still infer the Big Bang and today’s leading cosmological theory, known as ‘lambda-cold dark matter’ or LCDM. They will have to use the most distant light source available to them—’hypervelocity’ stars flung from the centre of Milkomeda.

“We used to think that observational cosmology wouldn’t be feasible a trillion years from now,” said Loeb, who directs the Institute for Theory and Computation at the Harvard-Smithsonian Centre for Astrophysics.

“Now we know this won’t be the case. Hypervelocity stars will allow Milkomeda residents to learn about the cosmic expansion and reconstruct the past.”

About once every 100,000 years, a binary-star system wanders too close to the black hole at our galaxy’s centre and gets ripped apart. One star falls into the black hole while the other is flung outward at a speed greater than 1.5 million kilometres per hour—fast enough to be ejected from the galaxy entirely.

No need for faith

Finding these hypervelocity stars is more challenging than spotting a needle in a haystack, but future astronomers would have a good reason to hunt diligently. Once they get far enough from Milkomeda’s gravitational pull, these stars will get accelerated by the universe’s expansion.

Andromeda galaxy

Andromeda, the nearest big galaxy, will one day merge with our Milky Way.

Astronomers could measure that acceleration with technologies more advanced than we have today. This would provide a different line of evidence for an expanding universe, similar to Hubble’s discovery but more difficult due to the very small effect being measured.

By studying stars within Milkomeda, they could infer when the galaxy formed. Combining that information with the hypervelocity star measurements, they could calculate the age of the universe and key cosmological parameters like the value of the cosmological constant (the lambda in LCDM).

“Astronomers of the future won’t have to take the Big Bang on faith. With careful measurements and clever analysis, they can find the subtle evidence outlining the history of the universe,” said Loeb.

This research appears in a paper accepted for publication in the Journal of Cosmology and Astroparticle Physics.

Adapted from information issued by CfA. Artwork courtesy David A. Aguilar (CfA). Hypervelocity star artwork courtesy NASA, ESA, and A. Feild (STScI). Andromeda image courtesy Caltech.

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Top astronomer joins Aussie uni

A spiral galaxy

Swinburne University's newest astronomy professor, Jeremy Mould, is a specialist in the hunt for the universe's 'dark matter'.

SWINBURNE UNIVERSITY’S REPUTATION as a world leader in astronomy research has been cemented, with the arrival of pre-eminent astrophysicist Professor Jeremy Mould.

A recipient of the prestigious Gruber Prize for Cosmology, Professor Mould is a ‘Hi-Ci’ researcher, putting him in the world’s top 0.5 per cent of cited researchers in the astronomy and space sciences field.

Professor Mould is Swinburne’s third Hi-Ci astronomy researcher, joining Centre for Astrophysics and Supercomputing Director, Professor Warrick Couch and galaxy expert Professor Karl Glazebrook.

With only ten active Hi-Ci astronomy researchers in all of Australia, this represents a significant cluster of world-leading experts at the one institution.

Professor Couch said that the centre’s newest arrival, who has come from the University of Melbourne, is one of the most respected researchers in the field of cosmology.

Professor Jeremy Mould

Professor Jeremy Mould

“Jeremy has an incredible record of achievement in astronomy research and management and we are extremely excited to have him on board,” he said.

“When it comes to leaders in his field, Jeremy really is the king of the castle.”

Focus on dark matter

Professor Mould is best known for his role in determining the precise value of the Hubble Constant, one of the most important numbers in astronomy.

This finding effectively determined the age of the universe (about 14 billion years), and has since enabled researchers to more accurately investigate other profound questions about the universe’s birth, evolution and composition.

As well as being a Hi-Ci researcher and recipient of the Gruber Prize, Professor Mould is also a Fellow of the Australian Academy of Science and a previous Director of the Research School of Astronomy and Astrophysics at the Australian National University and US National Optical Astronomy Observatories.

He is a chief investigator in the Australian Research Council’s new Centre of Excellence for All-Sky Astrophysics and leads its programme on the hunt for the mysterious dark matter. How dark matter is distributed on billion light year scales is his current focus. CSIRO’s new radiotelescope in WA is the key to this, together with the ANU’s new optical survey telescope at Siding Spring Observatory.

His arrival bolsters Swinburne’s place as one of the world’s leading astronomy research institutions.

In the Australian Research Council’s recent Excellence for Research in Australia report, Swinburne was awarded a five rating in the Astronomical Space Sciences category, recognising outstanding research that is well above world standard.

Adapted from information issued by Swinburne University.

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Sydney astronomer gets top science medal

Magnetic field lines superposed on a galaxy

Magnetic fields are spread throughout the universe, but their ultimate origin and evolution are still a mystery. Image courtesy Andrew Fletcher / Rainer Beck, SuW / Hubble Heritage Team, STScI / AURA.

ONE OF AUSTRALIA’S TOP science honours, the highly prestigious Pawsey Medal has been awarded to Bryan Gaensler, Professor of Physics at the Sydney Institute for Astronomy within the School of Physics at the University of Sydney.

The Pawsey Medal is awarded annually by the Australian Academy of Science and recognises outstanding Australian research in physics by scientists under 40 years of age.

Professor Bryan Gaensler

Professor Bryan Gaensler: "Australian astronomy is headed in some very exciting directions right now, and it's wonderful to be able to play a part in this adventure." Image courtesy University of Sydney.

This is the tenth occasion on which a staff member at the School of Physics has been awarded this honour, a remarkable achievement. Previous winners include Professor Kostya Ostrikov in 2008 and Professor Benjamin Eggleton in 2007.

Professor Gaensler received the award for his pioneering studies of cosmic magnetism, which have opened a new window on the Universe.

He has developed innovative new spectropolarimetric techniques, and has then used them to derive detailed three-dimensional maps of large-scale magnetic fields in the Milky Way, the Magellanic Clouds and in distant galaxies.

His experiments reveal what cosmic magnets look like and what role they have played in the evolving Universe. They have led to the selection of Cosmic Magnetism as a key science project for the Square Kilometre Array, a planned next-generation radio telescope for which Western Australia is one of the two contenders.

As a by-product of studying astrophysical magnetism, Professor Gaensler has also made the stunning discovery that the Milky Way is twice as thick as was previously thought, a result that fundamentally changes our understanding of our home Galaxy.

“It’s a huge honour to be recognised in this way by a body as distinguished as the Academy of Science,” Professor Gaensler said.

“Australian astronomy is headed in some very exciting directions right now, and it’s wonderful to be able to play a part in this adventure.”

Looking to the future, Professor Gaensler is about to take on a major new role as an Australian Laureate Fellow, commencing in early 2011. He plans to determine the overall magnetic field of the Universe, one of the final unsolved problems in cosmology.

Adapted from information issued by the University of Sydney.

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Matter vs antimatter

Nebulae in space

The Big Bang model suggests equal quantities of matter and antimatter should have formed, but the antimatter is nowhere to be seen out in space. A new experiment gives clues as to why matter has come to dominate.

  • Big Bang model suggests equal amounts of matter and antimatter
  • But only matter is seen widespread throughout the universe
  • New experiment gives clues as to why matter is dominant

A large collaboration of physicists working at the Fermilab Tevatron particle collider in the USA has found evidence for a possible explanation for the prevalence of matter over antimatter in the universe.

They found that smashing protons together in their experiment produced short-lived particles called “B mesons” that almost immediately broke down into debris that included slightly more matter than antimatter.

When particles of matter and antimatter collide, they annihilate each other and release energy. If there is slightly more matter to begin with, then all the antimatter will be annihilated, leaving a small excess of matter.

This sort of matter/antimatter asymmetry accounts for the fact that just about all the material in the universe is made of the normal matter we’re familiar with.

The Fermilab Tevatron

The Fermilab Tevatron (circular feature in background) is used to smash atomic particles together at high speed.

The Big Bang model suggests that equal amounts of matter and antimatter should have been formed, but the antimatter seems to have disappeared—everything in the universe seems to be made of normal matter. Why?

Physicists have long known about processes described by current physics theory that would produce tiny excesses of matter, but the amounts the theories predict are far smaller than necessary to create the universe we observe.

The Tevatron experiments suggest that we are on the verge of accounting for the quantities of matter that exist today.

But the truly exciting implication is that the experiment implies that there is new physics, beyond the widely accepted Standard Model, that must be at work.

If that’s the case, major scientific developments lie ahead.

The results emerge from a complicated and challenging analysis, and have yet to be confirmed by other experiments.

If the matter/antimatter imbalance holds up under the scrutiny of researchers at the Large Hadron Collider in Europe and competing research groups at Fermilab, it will likely stand as one of the most significant milestones in high-energy physics, according to Roy Briere of Carnegie Mellon University in Pittsburgh.

The results have been published in the journals Physical Review Letters and Physical Review D.

Adapted from information issued by APS / NASA / ESA / Orsola De Marco (Macquarie University).

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Cosmic baby photo

The all-sky microwave image of the universe made by the Planck space telescope.

The all-sky microwave image of the universe made by the Planck space telescope.

  • Map of the entire sky at microwave wavelengths
  • Shows the afterglow of the Big Bang
  • Will lead to better understanding of cosmic evolution

Scientists operating Europe’s space telescope, Planck, have released the mission’s first image of the whole sky.

“This is the moment that Planck was conceived for,” says European Space Agency (ESA) Director of Science and Robotic Exploration, David Southwood.

Planck picks up microwave wavelengths. What it sees are microwaves coming from near and far in the universe.

In particular, it is studying the microwave “glow” left over from the Big Bang 13.7 billion years ago—the cosmic microwave background radiation (CMBR). When we look at the CMBR, we’re seeing the oldest view we’ve ever had of the universe.

The CMBR has cooled right down from its fireball days, and is now at a temperature of about –270 degrees Celsius (only 2.7 degrees above absolute zero).

The new image is a map of the microwaves picked up from all different directions in space.

The oval shape of the map is similar to an oval-projection map of Earth, where cartographers take a round object (the Earth) and spread it out onto a flat shape. With Planck, it is a microwave map of the sky that is spread onto a flat surface.

Artist's impression of Planck

An artist's impression of the Planck telescope in its near-Earth location in space.

Why is the universe clumpy?

Stretching across the middle of the map is a mess of microwaves that come from sources within our Milky Way galaxy.

Of more interest is the mottled, reddish areas above and below. This is where Planck can see past the Milky Way to the distant universe beyond. The mottling comes from tiny temperature differences from one point to another in the CMBR.

In 1992, a forerunner of Planck, the Cosmic Microwave Background Explorer (COBE) spacecraft made the first detailed map of the CMBR. It showed the mottling effect.

The mottling effect is thought to reflect the way the universe has become “clumpy”—a combination of huge voids of empty space, and vast clusters and superclusters of galaxies.

Astronomers want to know why matter in the universe tended to clump into the clusters and superclusters, leaving the huge voids behind. It’s thought that the Big Bang explosion was “non-uniform”, ie. stuff spread out unevenly.

The mottling effect in the CMBR is thought to reflect that unevenness.

The initial discovery of the CMBR with ground-based antennae in 1964 led to its discoverers winning the Nobel Prize for Physics. This was followed by up another Nobel Prize for Physics in 2006 for two of the leaders of the COBE mission.

A scientific Eldorado

Planck is only a quarter of the way through its four-year mission. In that time, it will make four complete scans of the cosmos, building a very detailed map of the CMBR.

“We’re not giving the answer. We are opening the door to an Eldorado where scientists can seek the nuggets that will lead to deeper understanding of how our Universe came to be and how it works now,” says Southwood.

“The image itself and its remarkable quality is a tribute to the engineers who built and have operated Planck. Now the scientific harvest must begin.”

Story by Jonathan Nally, Editor, SpaceInfo.com.au

Images courtesy ESA / LFI & HFI Consortia / C. Carreau

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10-billion-year-old cosmos mapped

Thousands of galaxies crowd into this Herschel image of the distant Universe.

Thousands of galaxies crowd into this Herschel image of the distant Universe. Each dot is an entire galaxy containing billions of stars.

  • Early galaxies grouped near dark matter
  • Map made using Herschel Space Observatory
  • Largest telescope ever put into space

For more than a decade, astronomers have been puzzled by bright galaxies in the distant universe that appear to be forming stars at phenomenal rates. What prompted the prolific star creation, they wondered. And what kind of environment did these galaxies inhabit?

Now, using a super-sensitive camera/spectrometer on the Herschel Space Observatory, astronomers have mapped the skies as they appeared 10 billion years ago.

The scientists discovered that these glistening galaxies preferentially occupy regions of the universe containing more dark matter and that collisions probably caused the abundant star production.

“All indications are that these galaxies are…crashing, merging, and possibly settling down at centres of large dark-matter halos,” said Asantha Cooray of the University of California, Irvine (UCI).

The information will enable scientists to adapt conventional theories of galaxy formation to accommodate the strange, star-filled versions.

Artist's impression of the Herschel Space Telescope

Artist's impression of the Herschel Space Telescope.

Largest space telescope

The European Space Agency’s Herschel observatory carries the largest astronomical telescope operating in space today; it collects data at far-infrared wavelengths invisible to the naked eye.

One of three cameras on Herschel, SPIRE has let Cooray and colleagues survey large areas of the sky, about 60 times the size of the full Moon.

The data analysed in this study was among the first to come from the Herschel Multi-Tiered Extragalactic Survey, the space observatory’s largest project.

Seb Oliver, a University of Sussex professor who leads the survey, called the findings exciting.

“It’s just the kind of thing we were hoping for from Herschel,” he said, “and was only possible because we can see so many thousands of galaxies. It will certainly give the theoreticians something to chew over.”

The Herschel Multi-Tiered Extragalactic Survey will continue to collect images over larger areas of the sky in order to build up a more complete picture of how galaxies have evolved and interacted over the past 10 billion years.

Adapted from information issued by UC Irvine / ESA & SPIRE Consortium & HerMES consortia.

‘Galaxy genome’ project to start

A Hubble Space Telescope image of galaxies

The Galaxy Genome Project – an ambitious programme to create the definitive resource for studying galaxy evolution, the large-scale structure of the universe, and cosmology.

Move over, Craig Venter! Thanks to funding from the Australian Research Council (ARC), through its new Super Science Fellowships program, Australia’s national optical observatory is launching the Galaxy Genome Project – an ambitious programme to create the definitive resource for studying galaxy evolution, the large-scale structure of the universe, and cosmology.

“What the Human Genome Project did for biology, we’ll be doing for astronomy,” said Professor Matthew Colless, Director of the Anglo-Australian Observatory, Australia’s national centre for optical astronomy.

The AAO has been awarded four of the ARC’s new Super Science Fellowships to take this work forward, one starting in 2010 and three in 2011. Each Fellowship is worth $278,400 over three years. The successful applicants for the first round of Fellowships were announced by Senator Kim Carr, Minister for Science, in early April.

Galaxies are like people

Just as people are characterised by their genomes, a galaxy is characterised by the spectrum of its emitted light.

The 3.9m Anglo-Australian Telescope

The 3.9m Anglo-Australian Telescope is Australia's largest optical telescope, and the best of its kind in the world

The Galaxy Genome Project will combine 700,000 spectra from ongoing and completed surveys done with the AAO’s telescopes with 900,000 spectra from the next generation of surveys, to create the largest sample ever obtained by a single observatory—1.6 million spectra.

“This will increase by 50% the total number of galaxy spectra ever measured,” said Associate Professor Andrew Hopkins, Head of AAT Science at the Anglo-Australian Observatory. “We will create the primary and most thorough point of reference for all future studies of galaxy evolution.”

The AAT data will be combined with observations from new facilities such as the Australian National University’s (ANU’s) new SkyMapper telescope at Siding Spring Observatory in NSW, and the Australian SKA Pathfinder radio telescope, now being built by CSIRO in Western Australia.

“The Galaxy Genome Project will increase the scientific productivity and impact of all these major Australian investments,” Professor Colless said.

The project will also increase the international profile of Australian astronomy and enhance the prospects of Australian scientific and technical involvement in next-generation astronomical facilities such as the Square Kilometre Array (SKA), an international radio telescope, and the Giant Magellan Telescope (GMT), one of the next-generation “extremely large” optical telescopes or ELTs.

The domes of the Anglo-Australian Telescope and UK Schmidt Telescope

The domes of the Anglo-Australian Telescope and UK Schmidt Telescope

Combination of powerful surveys

Galaxy spectra reveal not only the redshifts (and hence distances) of galaxies, but also their dynamical state, their current and past rates of star formation, the degree to which they are obscured by dust, the abundances of elements in their stars and interstellar gas, and the total mass of stars and of dark matter. These are the keys to understanding galaxies’ origins and histories.

The Galaxy Genome Project has two phases. The first involves the consolidation of two complementary surveys, the Six-Degree Field Galaxy Survey (6dFGS) and the first stage of the Galaxy and Mass Assembly (GAMA) project.

6dFGS is a survey done with the AAO’s 1.2-m UK Schmidt Telescope. The most detailed survey to date of galaxies in the nearby Universe, it has recorded the positions of 125,000 galaxies over more than 80% of the southern sky, out to about 2,000 million light-years from Earth, with a volume and sampling five times larger than that of any previous survey.

GAMA-I, being carried out with the 3.9-m Anglo-Australian Telescope, is obtaining 1,000 galaxy spectra per square degree. This is an order of magnitude higher density than the ground-breaking Sloan Digital Sky Survey and 2dFGRS (Two-Degree Field Galaxy Redshift Survey), over an area of sky a hundred times larger than that of the most sensitive spectroscopic surveys to date.

A Hubble Space Telescope image of colliding galaxies

A Hubble Space Telescope image of colliding galaxies

GAMA-I thus allows the first large and systematic investigation of galaxy properties reaching down to the smallest galaxies.

Second phase will triple coverage

The second phase of the Galaxy Genome Project involves a continuation of GAMA, to triple the area of sky it covers, and a major new survey using the UK Schmidt Telescope called TAIPAN (Transforming Astronomical Imaging surveys through Polychromatic Analysis of Nebulae). TAIPAN will build on and extend the 6dFGS, adding 500,000 new spectra.

The 3.9-m Anglo-Australian Telescope is the largest optical telescope in Australia, and one of the world’s most productive.

The Anglo-Australian Observatory operates the AAT and the 1.2-m UK Schmidt Telescope, both located at Siding Spring Observatory in NSW. As its name suggests, it was created as a bi-national facility for UK and Australian astronomers.

On 1 July this year it will become a wholly Australian institution, and be incorporated into the Commonwealth Department of Innovation, Industry, Science and Research. The organisation will continue to be known as the AAO—now standing for the Australian Astronomical Observatory.

Adapted from information issued by AAO / Barnaby Norris / NASA / ESA / HHT / STScI / AURA.