RSSAll Entries Tagged With: "redshift"

Telescope takes universe’s temperature

Australia Telescope Compact Array

CSIRO’s Australia Telescope Compact Array, used the make the temperature measurements.

ASTRONOMERS USING a CSIRO radio telescope have taken the universe’s temperature, and have found that it has cooled down just the way the Big Bang theory predicts.

Using the Australia Telescope Compact Array near Narrabri, NSW, an international team from Sweden, France, Germany and Australia has measured how warm the universe was when it was half its current age.

“This is the most precise measurement ever made of how the universe has cooled down during its 13.77 billion year history,” said Dr Robert Braun, Chief Scientist at CSIRO Astronomy and Space Science.

Because light takes time to travel, when we look out into space we see the universe as it was in the past – as it was when light left the galaxies we are looking at. So to look back halfway into the universe’s history, we need to look halfway across the universe.

Cosmic fingerprint

How can we measure a temperature at such a great distance?

Illustration of radio waves coming from a distant quasar through a galaxy in the foreground and then on to Earth.

Radio waves from a distant quasar pass through another galaxy on their way to Earth. Changes in the radio waves indicate the temperature of the gas in that galaxy.

The astronomers studied gas in an unnamed galaxy 7.2 billion light-years away (at a redshift of 0.89).

The only thing keeping this gas warm is the cosmic background radiation – the glow left over from the Big Bang.

By chance, there is another powerful galaxy, a quasar (called PKS 1830-211), lying behind the unnamed galaxy.

Radio waves from this quasar come through the gas of the foreground galaxy. As they do so, the gas molecules absorb some of the energy of the radio waves. This leaves a distinctive ‘fingerprint’ on the radio waves.

From this ‘fingerprint’ the astronomers calculated the gas’s temperature. They found it to be 5.08 Kelvin (-267.92 degrees Celsius): extremely cold, but still warmer than today’s universe, which is at 2.73 Kelvin (-270.27 degrees Celsius).

Exactly as predicted

According to the Big Bang theory, the temperature of the cosmic background radiation drops smoothly as the universe expands.

“That’s just what we see in our measurements,” said research team leader Dr. Sebastien Muller of Onsala Space Observatory at Chalmers University of Technology in Sweden. “The universe of a few billion years ago was a few degrees warmer than it is now, exactly as the Big Bang theory predicts.”

Adapted from information issued by CSIRO. Images David Smyth and Onsala Space Observatory.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Galaxy at the dawn of time

Galaxy GN-108036

One of the most distant galaxies known, called GN-108036, is seen 750 million years after the Big Bang. The galaxy's light took 12.9 billion years to reach us. Infrared observations taken by NASA's Spitzer and Hubble space telescopes show it to be surprisingly bright, thought to result from an extreme burst of star formation

  • Galaxy seen as it was 750 million years after the Big Bang
  • Observations suggest it is forming stars at a furious rate

ASTRONOMERS USING NASA’S Spitzer and Hubble space telescopes have discovered that one of the most distant galaxies known is churning out stars at a shockingly high rate. The blob-shaped galaxy, called GN-108036, is the brightest galaxy found to date at such great distances.

The galaxy, which was discovered and confirmed using ground-based telescopes, is 12.9 billion light-years away.

Data from Spitzer and Hubble were used to measure the galaxy’s high star production rate, equivalent to about 100 Suns per year.

For reference, our Milky Way galaxy is about five times larger and 100 times more massive than GN-108036, but makes roughly 30 times fewer stars per year.

“The discovery is surprising because previous surveys had not found galaxies this bright so early in the history of the universe,” said Mark Dickinson of the US National Optical Astronomy Observatory in Arizona. “Perhaps those surveys were just too small to find galaxies like GN-108036.”

“It may be a special, rare object that we just happened to catch during an extreme burst of star formation.”

Seen shortly after the Big Bang

The international team of astronomers, led by Masami Ouchi of the University of Tokyo, Japan, first identified the remote galaxy after scanning a large patch of sky with the Subaru Telescope atop Mauna Kea in Hawaii.

Its great distance was then carefully confirmed with the W.M. Keck Observatory, also on Mauna Kea.

“We checked our results on three different occasions over two years, and each time confirmed the previous measurement,” said Yoshiaki Ono of the University of Tokyo, lead author of a new paper reporting the findings in the Astrophysical Journal.

Spitzer (left) and Hubble space telescopes

The Spitzer (left) and Hubble space telescopes were used to measure the galaxy's redshift, a indication of how far away it is.

GN-108036 lies near the very beginning of time itself, a mere 750 million years after our universe formed 13.7 billion years ago in an explosive “Big Bang.”

Its light has taken 12.9 billion years to reach us, so we are seeing it as it existed in the very distant past.

Remarkable redshift

Astronomers refer to an object’s distance by a number called its “redshift,” which is a measure of how much its light has been stretched to longer, redder wavelengths due to the expansion of the universe.

Objects with larger redshifts are farther away and are seen further back in time.

GN-108036 has a redshift of 7.2. Only a handful of galaxies have confirmed redshifts greater than 7, and only two of these have been reported to be more distant than GN-108036.

Infrared observations from Spitzer and Hubble were crucial for measuring the galaxy’s star-formation activity. Astronomers were surprised to see such a large burst of star formation because the galaxy is so small and from such an early cosmic era.

Back when galaxies were first forming, in the first few hundreds of millions of years after the Big Bang, they were much smaller than they are today, having yet to bulk up in mass.

During this epoch, as the universe expanded and cooled after its explosive start, hydrogen atoms permeating the cosmos formed a thick fog that was opaque to ultraviolet light. This period, before the first stars and galaxies had formed and illuminated the universe, is referred to as the “dark ages.”

The era came to an end when light from the earliest galaxies burned through, or “ionised,” the opaque gas, causing it to become transparent. Galaxies similar to GN-108036 may have played an important role in this event.

Adapted from information issued by NASA / JPL-Caltech / STScI / University of Tokyo.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Most distant quasar found

Artist’s impression of quasar ULAS J1120+0641

This artist’s impression shows how ULAS J1120+0641, a very distant quasar powered by a black hole with a mass two billion times that of the Sun, may have looked. This quasar is the most distant yet found and is seen as it was just 770 million years after the Big Bang.

ASTRONOMERS HAVE DISCOVERED the most distant quasar to date—a development that could help further our understanding of the universe when it was still in its infancy following the Big Bang.

Quasars are distant galaxies that have very bright cores, believed to be powered by supermassive black holes at their centres. Their brilliance makes them powerful beacons that may help to probe the era when the first stars and galaxies were forming.

“It is a very rare object that will help us to understand how supermassive black holes grew a few hundred million years after the Big Bang,” says Stephen Warren, the study’s team leader.

The quasar, named ULAS J1120+0641, is seen as it was only 770 million years after the Big Bang, giving it a redshift of 7.1. The light we see coming from it took 12.9 billion years to reach us.

Striking gold

Although more distant objects have been confirmed—such as a gamma-ray burst at redshift 8.2 and a galaxy at 8.6—the newly discovered quasar is hundreds of times brighter than these. In fact, amongst objects bright enough to be studied in detail, this is the most distant by a large margin.

Objects so away cannot be found in visible-light surveys because their light, stretched by the expansion of the Universe, falls mostly in the infrared part of the spectrum by the time it gets to Earth.

The European UKIRT Infrared Deep Sky Survey (UKIDSS) which uses the UK’s dedicated infrared telescope in Hawaii was designed to solve this problem. The team of astronomers hunted through millions of objects in the UKIDSS database to find those that could be the long-sought distant quasars, and eventually struck gold.

“It took us five years to find this object,” explains Bram Venemans, one of the authors of the study. “We were looking for a quasar with redshift higher than 6.5. Finding one that is this far away, at a redshift higher than 7, was an exciting surprise.”

A rare find

Because the object is comparatively bright it is possible to take a spectrum of it (which involves splitting the light from the object into its component colours). This technique enabled the astronomers to find out quite a lot about it.

These observations show that the mass of the black hole at the centre of ULAS J1120+0641 is about two billion times that of the Sun. This very high mass is hard to explain so early on after the Big Bang, as current theories for the growth of supermassive black holes predict a slow build-up in mass as the object pulls in matter from its surroundings.

“We think there are only about 100 bright quasars with redshift higher than 7 over the whole sky,” concludes Daniel Mortlock, the leading author of the paper. “Finding this object required a painstaking search, but it was worth the effort to be able to unravel some of the mysteries of the early Universe.”

Adapted from information issued by ESO / University of Nottingham / M. Kornmesser.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

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.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

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.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

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.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

First galaxies older than expected

Abell 383 and a distorted background galaxy

The gravity of this giant cluster of galaxies, including the huge one in the middle, acts as a sort of magnifying glass, distorting and concentrating the light of a distant background galaxy. Visible as two tiny dots (labelled), the galaxy is seen as it was less than a billion years after the Big Bang.

ASTRONOMERS HAVE DISCOVERED a distant galaxy whose stars were born unexpectedly early in cosmic history.

“We have discovered a distant galaxy that began forming stars just 200 million years after the Big Bang,” says Johan Richard, the lead author of a new study. “This challenges theories of how soon galaxies formed and evolved in the first years of the Universe.”

Richard’s team spotted the galaxy in recent observations from the NASA/ESA Hubble Space Telescope, verified it with observations from the NASA Spitzer Space Telescope and measured its distance using W.M. Keck Observatory in Hawaii.

The distant galaxy is far beyond a cluster of galaxies called Abell 383, whose powerful gravity bends passing rays of light almost like a magnifying glass.

The chance alignment of the galaxy, the cluster and the Earth amplifies the light reaching us from the distant galaxy, enabling the astronomers to make detailed observations.

Without this gravitational lens, the galaxy would have been too faint to be seen even with today’s largest telescopes.

A young galaxy of old stars

After spotting the galaxy in Hubble and Spitzer images, the team carried out spectroscopic observations with the Keck-II telescope in Hawaii. Spectroscopy is the technique of breaking up light into its component colours.

By analysing the spectra, the team was able to make detailed measurements of the galaxy’s redshift and infer information about the properties of its component stars.

The redshift is 6.027, which means we’re seeing the galaxy as it was when the Universe was around 950 million years old.

Diagram explaining gravitational lensing

The gravity of huge galaxy clusters acts as a magnifying glass, amplifying the light of galaxies in the distant background and making them easier to see.

This doesn’t make it the most remote galaxy ever detected—several have been confirmed at redshifts of more than 8, and one has an estimated redshift of around 10, placing it 400 million years earlier.

However the newly discovered galaxy is very different to other distant ones, which generally shine brightly with only young stars.

“When we looked at the spectra, two things were clear,” explains co-author Eiichi Egami. “The redshift placed it very early in cosmic history, as we expected. But the Spitzer infrared detection also indicated that the galaxy was made up of surprisingly old and relatively faint stars.”

“This told us that the galaxy was made up of stars already nearly 750 million years old—pushing back the epoch of its formation to about 200 million years after the Big Bang, much further than we had expected,” adds Egami.

“This suggests that the first galaxies have been around for a lot longer than previously thought,” says Dan Stark, another co-author of the study.

Artist's impression of the James Webb Space Telescope

When operational, the James Webb Space Telescope will be able to see even further back in time.

Unseen army may solve the mystery

The discovery has implications beyond the question of when galaxies first formed. It might also help explain how the Universe became transparent to ultraviolet light in the first billion years after the Big Bang.

In the early years of the cosmos, a diffuse fog of neutral hydrogen gas blocked ultraviolet light in the Universe. Some source of radiation must have progressively ionised the diffuse gas, clearing the fog and making it transparent to ultraviolet rays as it is today—a process known as reionisation.

Astronomers believe that the radiation that powered this reionisation must have come from galaxies. But, so far, nowhere near enough of them have been found to provide the necessary radiation.

The new discovery may help solve this enigma.

“It seems probable that there are in fact far more galaxies out there in the early Universe than we previously estimated—it’s just that many galaxies are older and fainter, like the one we have just discovered,” says co-author Jean-Paul Kneib.

“If this unseen army of faint, elderly galaxies is indeed out there, they could provide the missing radiation that made the Universe transparent to ultraviolet light.”

As of today, astronomers can discover these galaxies only by seeing them through gravitational lenses. But the NASA/ESA/CSA James Webb Space Telescope, scheduled for launch later this decade, will be able to make high-resolution observations of the distant, highly redshifted bodies.

Astronomers hope then to be in a position to solve this mystery once and for all.

Adapted from information issued by the ESA Hubble Information Centre. Abell 383 image courtesy of NASA, ESA, J. Richard (CRAL) and J.-P. Kneib (LAM) (acknowledgement: Marc Postman (STScI)). Gravitational lensing diagram courtesy NASA, ESA & L. Calçada.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz

Like this story? Please share or recommend it…

Galaxy at the edge of time

Portion of the Hubble Ultra Deep Field

The farthest and one of the very earliest galaxies ever seen in the universe appears as a faint red blob in this ultra-deep–field exposure taken with NASA's Hubble Space Telescope. This is the deepest infrared image taken of the universe. Based on the object's colour, astronomers believe it is 13.2 billion light-years away.

  • Using Hubble data, team spots galaxy with redshift of 10.3
  • We’re seeing it as it was 13.2 billion years ago

Astronomers studying ultra-deep imaging data from the Hubble Space Telescope have found what may be the most distant galaxy ever seen, about 13.2 billion light-years away.

The study pushed the limits of Hubble’s capabilities, extending its reach back to about 480 million years after the Big Bang, when the universe was just 4 percent of its current age.

“We’re getting back very close to the first galaxies, which we think formed around 200 to 300 million years after the Big Bang,” said Garth Illingworth, professor of astronomy and astrophysics at the University of California, Santa Cruz.

Illingworth and UCSC astronomer Rychard Bouwens (now at Leiden University in the Netherlands) led the study, which has been published in the January 27 issue of Nature.

Rapid build-up of galaxies

Using infrared data gathered by Hubble’s Wide Field Planetary Camera 3 (WFC3), they were able to see dramatic changes in galaxies over a period from about 480 to 650 million years after the Big Bang.

The rate of star birth in the universe increased by ten times during this 170-million-year period, Illingworth said.

“This is an astonishing increase in such a short period, just 1 percent of the current age of the universe,” he said.

There were also striking changes in the numbers of galaxies detected.

“Our previous searches had found 47 galaxies at somewhat later times when the universe was about 650 million years old. However, we could only find one galaxy candidate just 170 million years earlier,” Illingworth said. “The universe was changing very quickly in a short amount of time.”

According to Bouwens, these findings are consistent with the hierarchical picture of galaxy formation, in which galaxies grew and merged under the gravitational influence of dark matter.

“We see a very rapid build-up of galaxies around this time,” he said. “For the first time now, we can make realistic statements about how the galaxy population changed during this period and provide meaningful constraints for models of galaxy formation.”

Here’s a NASA video with some comments from Garth Illingworth:

Remarkable redshift

Astronomers gauge the distance of an object from its redshift, a measure of how much the expansion of space has stretched the light from an object to longer (“redder”) wavelengths.

The newly detected galaxy has a likely redshift value (“z”) of 10.3, which corresponds to an object that emitted the light we now see 13.2 billion years ago, just 480 million years after the birth of the universe.

“This result is on the edge of our capabilities, but we spent months doing tests to confirm it, so we now feel pretty confident,” Illingworth said.

The galaxy, a faint smudge of starlight in the Hubble images, is tiny compared to the massive galaxies seen in the local universe. Our own Milky Way, for example, is more than 100 times larger.

The researchers also described three other galaxies with redshifts greater than 8.3. The study involved a thorough search of data collected from deep imaging of the Hubble Ultra Deep Field (HUDF), a small patch of sky about one-tenth the size of the Moon.

During two four-day stretches in summer 2009 and summer 2010, Hubble focused on one tiny spot in the HUDF for a total exposure of 87 hours with the WFC3 infrared camera.

Graph showing ability of different telescopes to look increasingly deeper back into time

Timeline of time: Over the years, improvements in technology have enabled astronomers to use their telescopes to peer further and further back into time. The forthcoming James Webb Space Telescope will be able to see even further.

Next step? Hubble’s successor

To go beyond redshift 10, astronomers will have to wait for Hubble’s successor, the James Webb Space Telescope (JWST), which NASA plans to launch later this decade. JWST will also be able to perform the spectroscopic measurements needed to confirm the reported galaxy at redshift 10.

“It’s going to take JWST to do more work at higher redshifts. This study at least tells us that there are objects around at redshift 10 and that the first galaxies must have formed earlier than that,” Illingworth said.

Illingworth’s team maintains the First Galaxies website, with information about the latest research on distant galaxies: http://firstgalaxies.org/

In addition to Bouwens and Illingworth, the co-authors of the Nature paper include Ivo Labbe of Carnegie Observatories; Pascal Oesch of UCSC and the Institute for Astronomy in Zurich; Michele Trenti of the University of Colorado; Marcella Carollo of the Institute for Astronomy; Pieter van Dokkum of Yale University; Marijn Franx of Leiden University; Massimo Stiavelli and Larry Bradley of the Space Telescope Science Institute; and Valentino Gonzalez and Daniel Magee of UC Santa Cruz.

The research was supported by NASA and the Swiss National Science Foundation.

Adapted from information issued by UCSC. Images credit: NASA, ESA, Garth Illingworth (UC Santa Cruz), Rychard Bouwens (UC Santa Cruz and Leiden University) and the HUDF09 Team / A. Feild (STScI).

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz