Behold The Distant Universe!

An image of a small section (0.4%) of the UDS field - showing a series of very distant galaxies as they appeared 9 billion years ago. Credit: Omar Almaini, University of Nottingham

This past Monday (June 27th), the National Astronomy Meeting – which is hosted by the Royal Astronomy Society – kicked off at the University of Nottingham in the UK. As one of the largest professional conferences in Europe (with over 500 scientists in attendance), this annual meeting is an opportunity for astronomers and scientists from a variety of fields to present that latest in their research.

And of the many presentations made so far, one of the most exciting came from a research team from the University of Nottingham’s School of Physics and Astronomy, which presented the latest near-infrared images obtained by the Ultra Deep Survey (UDS). In addition to being a spectacular series of pictures, they also happened to be the deepest view of the Universe to date.

The UDS survey, which began in 2005, is one of the five projects that make up the UKIRT’s Infrared Deep Sky Survey (UKIDSS). For the sake of their survey, the UDS team relies on the Wide Field Camera (WFCAM) on the United Kingdom Infrared Telescope in Mauna Kea, Hawaii. At 3.8-metres in diameter, the UKIRT is the world’s second largest telescope dedicated to infrared astronomy.

As Professor Omar Almaini, the head of the University of Nottingham research team, explained to Universe Today via email:

“The UDS is by far the deepest near-infrared survey over such a large, contiguous area (0.8 sq degrees). There is only one other similar survey, which is known as UltraVISTA. It covers a larger area (1.5 sq degree) but is not quite so deep. Together the UDS and UltraVISTA should revolutionize studies of the high-redshift Universe over the next few years.”

Ultimately, the goal of UDS is shed light on how and when galaxies form, and to chart their evolution over the course of the last 13 billion years (roughly 820 million years after the Big Bang). For over a decade, the UDS has been observing the same patch of sky repeatedly, relying on optical and infrared imaging to ensure that the light of distant objects (which is redshifted due to the profound distances involved) can be captured.

“Stars emit most of their radiation at optical wavelengths, which is redshifted to the near-infrared at high redshift,” said Almaini. “Near-infrared surveys therefore provide the least biased census of galaxies in the early Universe and the best measurements of the stellar mass. Deep optical surveys will only detect galaxies that are bright in the rest-frame ultraviolet, so they are biased against galaxies that are obscured by dust, or those that have stopped forming stars.”

In total, the project has accumulated more than 1000 hours of exposure time, detecting over two hundred and fifty thousand galaxies – several hundred of which were observed within the first billion years after the Big Bang. The final images, which were released yesterday and presented at the National Astronomy Meeting, showed an area four times the size of the full Moon, and at an unprecedented depth.

Data previously released by the UDS project has already led to several scientific advances. These include studies of the earliest galaxies in the Universe after the Big Bang, measurements on the build-up of galaxies over time, and studies of the large-scale distribution of galaxies to measure the influence of dark matter.

With this latest release, many more are anticipated, with astronomers around the world spending the next few years studying the early stages of galaxy formation and evolution. As Almaini put it:

“With the UDS (and UltraVISTA) we now have the ability to study large samples of galaxies in the distant Universe, rather than just a handful. With thousands of galaxies at each epoch we can perform detailed comparisons of the evolving galaxy populations, and we can also study their large-scale structure to understand how they trace the underlying cosmic web of dark matter. With large samples we can also look for rare but important populations, such as those in transition.”

“A key aim is to understand why many massive galaxies abruptly stop forming stars around 10 billion years ago, and also how they transform from disk-like systems into elliptical galaxies. We have recently identified a few hundred examples of galaxies in the process of transformation at early times, which we are actively studying to understand what is driving the rapid changes.”

Along with the subject of galaxy surveys and large scale structure, “galaxy formation and evolution” and “galaxy surveys and large scale structure” were two of the 2016 National Astronomy Meeting’s main themes. Naturally, the UDS release fit neatly into both categories. The others themes included the Sun, stars and planetary science, gravitational waves, modified gravity, archeoastronomy, astrochemistry, and education and outreach.

The Meeting will run until tomorrow (Friday, July 1st), and also included a presentations on the latest infrared images of Jupiter, which were taken by the ESO in preparation for the Juno spacecraft’s arrival on July 4th.

Further Reading: Royal Astronomical Society

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Japanese 3D Galaxy Map Confirms Einstein Was One Smart Dude

An international team of researchers have produced the largest  3-D map of the universe to date, which validates Einstein's theory of General Relativity. Credit: NAOJ/CFHT/ SDSS

On June 30th, 1905, Albert Einstein started a revolution with the publication of theory of Special Relativity. This theory, among other things, stated that the speed of light in a vacuum is the same for all observers, regardless of the source. In 1915, he followed this up with the publication of his theory of General Relativity, which asserted that gravity has a warping effect on space-time. For over a century, these theories have been an essential tool in astrophysics, explaining the behavior of the Universe on the large scale.

However, since the 1990s, astronomers have been aware of the fact that the Universe is expanding at an accelerated rate. In an effort to explain the mechanics behind this, suggestions have ranged from the possible existence of an invisible energy (i.e. Dark Energy) to the possibility that Einstein’s field equations of General Relativity could be breaking down. But thanks to the recent work of an international research team, it is now known that Einstein had it right all along.

Using the Fiber Multi-Object Spectrograph (FMOS) on the Subaru Telescope, the team – which was led by researchers from Japan’s Institute for the Physics and Mathematics of the Universe (Kavli IMPU) and the University of Tokyo – created the deepest 3-D map of the Universe to date. All told, this map contains some 3,000 galaxies and encompasses a volume of space measuring 13 billion light-years.

To test Einstein’s theory, the team  – which was led by Dr. Teppei Okumura, a Kavli IPMU Project Researcher – used information obtained by the FastSound Project over the past few years. As part of their effort to ascertain the origins of cosmic acceleration, this project relies on data collected by the Subaru telescope to create a survey that monitors the redshift of galaxies.

From what was observed over the course of 40 nights (between 2012 and 2014), the FastSound Survey was able to determine the on velocities and clustering of more than 3,000 distant galaxies. Measuring their redshift space distortions to see how fast they were moving, Okumura and his team were able to track the expansion of these galaxies out to a distance of 13 billion light-years.

This was an historic feat, seeing as how previous 3-D models of the Universe have not been able to reach beyond 10 billion light years. But thanks to the FMOS on the Subaru Telescope, which can analyze galaxies 12.4 to 14.7 billion light-years away, the team was able to break this record. They then compared the results to the kind of expansion predicted by Einstein’s theory, particularly the inclusion of his cosmological constant.

Originally introduced by Einstein in 1917 as an addition to his theory of General Relativity, the cosmological constant was basically a way to hold back gravity and achieve a static Universe. And while Einstein abandoned this theory when Edwin Hubble discovered that the Universe was expanding, it has since come to be an accepted part of the standard model of modern cosmology (known as the Lambda-CDM model).

https://youtu.be/RAiPZ_oUPI4

What the research team found was that even at a distance of 13 billion light-years into the Universe, the rules of General Relativity are still valid. “We tested the theory of general relativity further than anyone else ever has,” said Dr. Okumura. “It’s a privilege to be able to publish our results 100 years after Einstein proposed his theory.”

These results have helped resolve something that astronomers have been puzzling over for decades, which was whether or not Einstein’s cosmological constant could be shown to be consistent with an expanding Universe. And while various experiments have confirmed that General Relativity did match observational data, they have been somewhat limited in the past.

For example, the Pound-Rebka experiment, which took place in 1960, was the first confirmation of Einstein’s theory. However, this experiment, and the many that followed in the ensuing decades, were either indirect or confined to the Solar System. A 2010 experiment conducted by researchers from Princeton University confirmed General Relativity to a distance of 7 billion light years.

But with this experiment, General Relativity has been confirmed to a distance of 13 billion light years, which accounts for the vast majority of the Universe that we can see (which is 13.8 billion light-years). It seems that even a century later, Einstein’s theories are still holding up. And considering that he once claimed that the cosmological constant was the “biggest blunder” of his scientific career!

Further Reading: Publications of the Astronomical Society of Japan

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Astronomy Cast Ep. 412: The Color of the Universe

What color is the Universe? Turns out this isn’t a simple question, and one that scientists have really been unable to answer, until now! Visit the Astronomy Cast Page to subscribe to the audio podcast! We record Astronomy Cast as a live Google+ Hangout on Air every Monday at 12:00 pm Pacific / 3:00 pm […]

The post Astronomy Cast Ep. 412: The Color of the Universe appeared first on Universe Today.

New Lenses To Help In The Hunt For Dark Energy

MayallStarTrails-s

Since the 1990s, scientists have been aware that for the past several billion years, the Universe has been expanding at an accelerated rate. They have further hypothesized that some form of invisible energy must be responsible for this, one which makes up 68.3% of the mass-energy of the observable Universe. While there is no direct evidence that this “Dark Energy” exists, plenty of indirect evidence has been obtained by observing the large-scale mass density of the Universe and the rate at which is expanding.

But in the coming years, scientists hope to develop technologies and methods that will allow them to see exactly how Dark Energy has influenced the development of the Universe. One such effort comes from the U.S. Department of Energy’s Lawrence Berkeley National Lab, where scientists are working to develop an instrument that will create a comprehensive 3D map of a third of the Universe so that its growth history can be tracked.

Known as the Dark Energy Spectroscopic Instrument (DESI), this project plans to start with the present day, pinpointing the locations of galaxies in the Universe, and then work backwards into the past. DESI officially kicked off with the recent delivery of two new and improved lenses to the Mayall Telescope at the Kitt Peak National Observatory in Arizona.

The first of six such upgrades, these two new lenses – Corrector Lens 1 and Corrector Lens 4 (C1 and C4) – have been in production since early 2015. Measuring 1 meter in diameter and weighing 201.395 kg (444 pounds) and 236.775 kg (522 pounds), respectively, these lenses are scheduled to undergo a final antireflective coating before being integrated into the Mayall telescope’s new steel corrector barrel.

Each of these lenses comes equipped with 5000 optical fibers, similar to kind of cables used for high-speed data traffic (i.e. internet and telecommunications). They will give the 4-meter telescope a very wide field of view and be able to detect the light coming from 5000 galaxies at a time. This light will then be directed to the 30 cameras and spectrographs that are connected to the Mayall telescope, which the science team will then measure to gauge its redshift.

For many years, the Berkeley Lab has been measuring the redshift of distant galaxies – the ratio of the wavelength that is seen to the wavelength the light had when it left the galaxy – to gauge their distances from our Solar System. However, since light will stretch exactly the way the universe stretches, these measurements have also been giving the Berkeley scientists an idea of how the universe is expanding.

Once the entire DESI package is assembled – which is expected to happen by 2018 – it will begin collecting spectrographic information on a total of 35 million distant galaxies and quasars. This information will then be used to construct the largest 3D map of the Universe, one that spans 10 billion light years. This will allow DESI scientists to not only survey the large-scale structure of the Universe, but also look back in time and see how the Universe changed over the past 10 billion years.

However, redshift alone can only provide astronomers with relative distances. In order to create the 3D map with a genuine sense of scale, the DESI scientists will also be relying on baryon acoustic oscillations – which are periodic fluctuations in the density of the visible baryonic matter of the universe. Together, these measurements of the changing distance between galaxies could show us exactly how Dark Matter influences cosmic expansion.

DESI is undeniably the next wave of innovation when it comes to how we observe the Universe, combing high-performance optics with  computer-assisted analysis. And when the map is finally complete, scientists may begin to see exactly how this mysterious energy that permeates our Universe has influenced its expansion and evolution.

Another step on the long, winding road from theory to knowing!

Further Reading: Berkeley Lab, DESI

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Farthest Galaxy Ever Seen Viewed By Hubble Telescope

Galaxy GN-z11 superimposed on an image from the GOODS-North survey. Credit: NASA/ESA/P. Oesch (Yale University)/G. Brammer (STScI)/P. van Dokkum (Yale University)/G. Illingworth (University of California, Santa Cruz)

Since it was first launched in 1990, the Hubble Space Telescope has provided people all over the world with breathtaking views of the Universe. Using its high-tech suite of instruments, Hubble has helped resolve some long-standing problems in astronomy, and helped to raise new questions. And always, its operators have been pushing it to the limit, hoping to gaze farther and farther into the great beyond and see what’s lurking there.

And as NASA announced with a recent press release, using the HST, an international team of astronomers just shattered the cosmic distance record by measuring the farthest galaxy ever seen in the universe. In so doing, they have not only looked deeper into the cosmos than ever before, but deeper into it’s past. And what they have seen could tell us much about the early Universe and its formation.

Due to the effects of special relativity, astronomers know that when they are viewing objects in deep space, they are seeing them as they were millions or even billions of years ago. Ergo, an objects that is located 13.4 billions of light-years away will appear to us as it was 13.4 billion years ago, when its light first began to make the trip to our little corner of the Universe.

This is precisely what the team of astronomers witnessed when they gazed upon GN-z11, a distant galaxy located in the direction of the constellation of Ursa Major. With this one galaxy, the team of astronomers – which includes scientists from Yale University, the Space Telescope Science Institute (STScI), and the University of California – were able to see what a galaxy in our Universe looked like just 400 million years after the Big Bang.

Prior to this, the most distant galaxy ever viewed by astronomers was located 13.2 billion light years away. Using the same spectroscopic techniques, the Hubble team confirmed that GN-z11 was nearly 200 million light years more distant. This was a big surprise, as it took astronomers into a region of the Universe that was thought to be unreachable using the Hubble Space Telescope.

In fact, astronomers did not suspect that they would be able to probe this deep into space and time without using Spitzer, or until the deployment the James Webb Space Telescope – which is scheduled to launch in October 2018. As Pascal Oesch of Yale University, the principal investigator of the study, explained:

“We’ve taken a major step back in time, beyond what we’d ever expected to be able to do with Hubble. We see GN-z11 at a time when the universe was only three percent of its current age. Hubble and Spitzer are already reaching into Webb territory.”

In addition, the findings also have some implications for previous distance estimates. In the past, astronomers had estimated the distance of GN-z11 by relying on Hubble and Spitzer’s color imaging techniques. This time, they relied on Hubble’s Wide Field Camera 3 to spectroscopically measure the galaxies redshift for the first time. In so doing, they determined that GN-z11 was farther way than they thought, which could mean that some particularly bright galaxies who’s distanced have been measured using Hubble could also be farther away.

The results also reveal surprising new clues about the nature of the very early universe. For starters, the Hubble images (combined with data from Spitzer) showed that GN-z11 is 25 times smaller than the Milky Way is today, and has just one percent of our galaxy’s mass in stars. At the same time, it is forming stars at a rate that is 20 times greater than that of our own galaxy.

As Garth Illingworth – one of the team’s investigator’s from the University of California, Santa Cruz – explained:

“It’s amazing that a galaxy so massive existed only 200 million to 300 million years after the very first stars started to form. It takes really fast growth, producing stars at a huge rate, to have formed a galaxy that is a billion solar masses so soon. This new record will likely stand until the launch of the James Webb Space Telescope.”

Last, but not least, they provide a tantalizing clue as to what future missions – like the James Webb Space Telescope – will be finding. Once deployed, astronomers will likely be looking ever farther into space, and farther into the past. With every step, we are closing in on seeing what the very first galaxies that formed in our Universe looked like.

https://youtu.be/vgQdQx3V1HY

Further Reading: NASA

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Missing Matter Found! Fast Radio Bursts Confirm Cosmological Model

Researchers at the CSIRO have managed to pinpoint the location of an FRB for the first time, yielding valuable information about our universe. Credit: csiro.au

In March 2013, researchers at the CERN laboratory made history when they announced the discovery of the Higgs Boson. Though its existence had been hypothesized for over half a century, confirming its existence was a major boon for scientists. In discovering this one particle, the researchers were also able to confirm the Standard Model of particle physics. Much the same is true of our current cosmological model.

For decades, scientists been going by the theory that the Universe is made of 70% dark energy, 25% dark matter and 5% “luminous matter” – i.e. the matter we can see. But even when all the visible matter is added up, there is a discrepancy where much of it is still considered “missing”. But thanks to the efforts of a team from the Commonwealth Scientific and Industrial Research Organization (CSIRO), scientists now know that we have it right.

This began on April 18th, 2015, when the CSIRO’s Parkes Observatory in Australia detected a fast radio burst (FRB) coming from space. An international alert was immediately issued, and within a few hours, telescopes all around the world were looking for the signal. The CSIRO team began tracking it as well with the Australian Telescope Compact Array (ATCA) located at the Paul Wild Observatory (north of Parkes).

With the help of the National Astronomical Observatory of Japan’s (NAOJ) Subaru telescope in Hawaii, they were able to pinpoint where the signal was coming from. As the CSIRO team described in a paper submitted to Nature, they identified the source, which was an elliptical galaxy located 6 billion light years from Earth.

This was an historic accomplishment, since pinpointing the source of FRBs have never before been possible. Not only do the signals last mere milliseconds, but they are also subject to dispersion – i.e. a delay caused by how much material they pass through. And while FRBs have been detected in the past, the teams tracking them have only been able to obtain measurements of the dispersion, but never the signal’s redshift.

Redshift occurs as a result of an object moving away at relativistic speeds (a portion of the speed of light). For decades, scientists have been using it to determine how fast other galaxies are moving away from our own, and hence the rate of expansion of the Universe. Relying on optical data obtained by the Subaru telescope, the CSIRO team was able to obtain both the dispersion and the redshift data from this signal.

https://www.skatelescope.org/wp-content/uploads/2016/02/FRBs.FinalCandidate5-HD.mp4

As stated in their paper, this information yielded a “direct measurement of the cosmic density of ionized baryons in the intergalactic medium”. Or, as Dr. Simon Johnston – of the CSIRO’s Astronomy and Space Science division and the co-author of the study – explains, the team was not only to locate the source of the signal, but also obtain measurements which confirmed the distribution of matter in the Universe.

“Until now, the dispersion measure is all we had,” he said. “By also having a distance we can now measure how dense the material is between the point of origin and Earth, and compare that with the current model of the distribution of matter in the Universe. Essentially this lets us weigh the Universe, or at least the normal matter it contains.”

Dr. Evan Keane of the SKA Organization, and lead author on the paper, was similarly enthused about the team’s discovery. “[W]e have found the missing matter,” he said. “It’s the first time a fast radio burst has been used to conduct a cosmological measurement.”

As already noted, FRB signals are quite rare, and only 16 have been detected in the past. Most of these were found by sifting through data months or years after the signal was detected, by which time it would be impossible for any follow-up observations. To address this, Dr. Keane and his team developed a system to detect FRBs and immediately alert other telescopes, so that the source could be pinpointed.

It is known as the Square Kilometer Array (SKA), an international effort led by the SKA Organization to build the world’s largest radio telescope. Combining extreme sensitivity, resolution and a wide field of view, the SKA is expected to trace many FRBs to their host galaxies. In so doing, it is hoped the array will provide more measurements confirming the distribution of matter in the Universe, as well as more information on dark energy.

In the end, these and other discoveries by the SKA could have far-reaching consequences. Knowing the distribution of matter in the universe, and improving our understanding of dark matter (and perhaps even dark energy) could go a long way towards developing a Theory Of Everything (TOE). And knowing how all the fundamental forces of our universe interact will go a long way to finally knowing with certainty how it came to be.

These are exciting time indeed. With every step, we are peeling back the layers of our universe!

Further Reading: CSIRO, SKA Organization, Nature.

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How Can Space Travel Faster Than The Speed Of Light?

Cosmologists are intellectual time travelers. Looking back over billions of years, these scientists are able to trace the evolution of our Universe in astonishing detail. 13.8 billion years ago, the Big Bang occurred. Fractions of a second later, the fledgling Universe expanded exponentially during an incredibly brief period of time called inflation. Over the ensuing eons, […]