Ultra-distant galaxy discovered amidst cosmic 'dark ages': May be oldest galaxy ever

ScienceDaily (Sep. 19, 2012) — With the combined power of NASA's Spitzer and Hubble space telescopes as well as a cosmic magnification effect, a team of astronomers led by Wei Zheng of The Johns Hopkins University has spotted what could be the most distant galaxy ever detected.

Light from the young galaxy captured by the orbiting observatories shone forth when the 13.7-billion-year-old universe was just 500 million years old.

The far-off galaxy existed within an important era when the universe began to transit from the so-called "Dark Ages." During this period, the universe went from a dark, starless expanse to a recognizable cosmos full of galaxies. The discovery of the faint, small galaxy accordingly opens up a window into the deepest, remotest epochs of cosmic history.

"This galaxy is the most distant object we have ever observed with high confidence," said Zheng, a principal research scientist in The Henry A. Rowland Department of Physics and Astronomy at Johns Hopkins' Krieger School of Arts and Sciences and lead author of a paper appearing in Nature on Sept. 20. "Future work involving this galaxy -- as well as others like it that we hope to find -- will allow us to study the universe's earliest objects and how the Dark Ages ended."

Light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching NASA's telescopes. In other words, the starlight snagged by Spitzer and Hubble left the galaxy when the universe was just 3.6 percent of its present age. Technically speaking, the galaxy has a redshift, or "z," of 9.6. The term "redshift" refers to how much an object's light has shifted into longer wavelengths as a result of the expansion of the universe. Astronomers use "redshift" to describe cosmic distances.

Unlike previous detections of galaxy candidates in this age range, which were only glimpsed in a single color, or waveband, this newfound galaxy has been seen in five different wavebands. As part of the Cluster Lensing and Supernova Survey with Hubble program (CLASH), the Hubble Space Telescope registered the newly described far-flung galaxy in four wavelength bands. Spitzer located it in a fifth band with its Infrared Array Camera (IRAC), placing the discovery on firmer ground.

Objects at these extreme distances are mostly beyond the detection sensitivity of today's largest telescopes. To catch sight of these early, distant galaxies, astronomers rely on "gravitational lensing." In this phenomenon -- predicted by Albert Einstein a century ago -- the gravity of foreground objects warps and magnifies the light from background objects. A massive galaxy cluster situated between our galaxy and the early galaxy magnified the latter's light, brightening the remote object some 15 times and bringing it into view.

Based on the Spitzer and Hubble observations, astronomers think the distant galaxy was spied at a time when it was less than 200 million years old. It also is small and compact, containing only about 1 percent of the Milky Way's mass. According to leading cosmological theories, the first galaxies should indeed have started out tiny. They then progressively merged, eventually accumulating into the sizable galaxies of the more modern universe.

These first galaxies likely played the dominant role in the epoch of reionization, the event that signaled the demise of the universe's Dark Ages. About 400,000 years after the Big Bang, neutral hydrogen gas formed from cooling particles. The first luminous stars and their host galaxies, however, did not emerge until a few hundred million years later. The energy released by these earliest galaxies is thought to have caused the neutral hydrogen strewn throughout the universe to ionize, or lose an electron, the state in which the gas has remained since that time.

"In essence, during the epoch of reionization, the lights came on in the universe," said paper co-author Leonidas Moustakas, a research scientist at NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif.

Astronomers plan to study the rise of the first stars and galaxies and the epoch of reionization with the successor to both Spitzer and Hubble -- NASA's James Webb Telescope, slated for launch in 2018. The newly described distant galaxy will likely be a prime target.

Holland Ford, one of Zheng's colleagues and a co-author on the paper, commented on the findings.

"Science is very exciting when we explore the frontiers of knowledge," said Ford, a physics and astronomy professor at Johns Hopkins. "One of these frontiers is the first few hundred million years after the birth of our universe. Dr. Zheng's many years of searching for quasars and galaxies in the dawn of the universe has paid off with his discovery of a galaxy that we see as it was when the universe was less than 500 million years old.

"With his discovery, we are seeing a galaxy when it was not even a toddler," Ford said. "But this infant galaxy will in its future grow to be a galaxy like our own, hopefully hosting planetary systems with astronomers who will look back in time and see our galaxy in its infancy."

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The above story is reprinted from materials provided by Johns Hopkins University, via Newswise. The original article was written by Lisa DeNike.

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Journal Reference:

1. Wei Zheng, Marc Postman, Adi Zitrin, John Moustakas, Xinwen Shu, Stephanie Jouvel, Ole Høst, Alberto Molino, Larry Bradley, Dan Coe, Leonidas A. Moustakas, Mauricio Carrasco, Holland Ford, Narciso Benítez, Tod R. Lauer, Stella Seitz, Rychard Bouwens, Anton Koekemoer, Elinor Medezinski, Matthias Bartelmann, Tom Broadhurst, Megan Donahue, Claudio Grillo, Leopoldo Infante, Saurabh W. Jha, Daniel D. Kelson, Ofer Lahav, Doron Lemze, Peter Melchior, Massimo Meneghetti, Julian Merten, Mario Nonino, Sara Ogaz, Piero Rosati, Keiichi Umetsu, Arjen van der Wel. A magnified young galaxy from about 500 million years after the Big Bang. Nature, 2012; 489 (7416): 406 DOI: 10.1038/nature11446

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20 Sep, 2012

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CT scan and 3-D print help scientists reconstruct an ancient mollusk

ScienceDaily (Sep. 19, 2012) — Using a combination of traditional and innovative model-building techniques, scientists in the U.S. and a specialist in Denmark have created a lifelike reconstruction of an ancient mollusk, offering a vivid portrait of a creature that lived about 390 million years ago, and answering questions about its place in the tree of life, as described in the Sept. 18 edition of the journal Palaeontology.

The model of the oval-shaped sea creature, called a multiplacophoran, which was covered with stiff plates and a ring of spines, resulted from a collaboration between Jakob Vinther, a postdoctoral researcher at The University of Texas at Austin's Jackson School of Geosciences, and Esben Horn, owner of the model making company 10 Tons in Copenhagen (http://www.10tons.dk), with animation help from Ryan Carney, a doctoral student at Brown University.

Working with a delicate specimen of a multiplacophoran partially covered by rock, Vinther used a micro CT scan -- a noninvasive technology similar to medical CAT scanning -- to create a three-dimensional view of the fossil. With Carney's help, the CT scan yielded an animated view of the original placement of the creature's dense spines and shells, which had splayed out and decayed prior to fossilization.

The CT scan also produced a three-dimensional cast of the specimen in its reconstructed shape. Working with the cast, the animation and information on living relatives of the multiplacophorans, Horn was able to create a multicolored, textured model in clay, resin and silicone showing how the creature looked millions of years ago, when it crawled on a single, suction-like foot over shells and rocky surfaces in ancient oceans.

The model helps address a debate about how multiplacophorans (which were only discovered in the past decade) relate to chitons, another more widely known plated mollusk that lives on seashores and is commonly eaten in the Caribbean. By dating the origin of modern chitons, Vinther could demonstrate that multiplacophorans are stem group chitons.

"We can now demonstrate that multiplacophorans are distant relatives of the modern chitons, which did not evolve until later in Earth history," said Vinther. "We can also show that they evolved a number of characteristics seen in some modern chitons convergently."

The CT scan was integral to the project, allowing the scientists to see below the surface of the fossil.

"CT scanning is an extremely powerful technique for paleontologists," said Vinther, "since we can look inside fossils without destroying them."

The original fossil was discovered 10 years ago in Ohio by private collector and co-author George Kampouris, who donated it to the Cincinnati Museum of Natural History.

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The above story is reprinted from materials provided by University of Texas at Austin.

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Journal Reference:

1. Jakob Vinther, Peter Jell, George Kampouris, Ryan Carney, Rachel A. Racicot, Derek E. G. Briggs. The origin of multiplacophorans - convergent evolution in Aculiferan molluscs. Palaeontology, 2012; 55 (5): 1007 DOI: 10.1111/j.1475-4983.2012.01180.x

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20 Sep, 2012

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How organisms evolve new functions: Evolution is as complicated as 1-2-3

ScienceDaily (Sep. 19, 2012) — A team of researchers at Michigan State University has documented the step-by-step process in which organisms evolve new functions.

The results, published in the current issue of Nature, are revealed through an in-depth, genomics-based analysis that decodes how E. coli bacteria figured out how to supplement a traditional diet of glucose with an extra course of citrate.

"It's pretty nifty to see a new biological function evolve," said Zachary Blount, postdoctoral researcher in MSU's BEACON Center for the Study of Evolution in Action. "The first citrate-eaters were just barely able to grow on the citrate, but they got much better over time. We wanted to understand the changes that allowed the bacteria to evolve this new ability. We were lucky to have a system that allowed us to do so."

Normal E. coli can't digest citrate when oxygen is present. In fact, it's a distinct hallmark of E. coli. They can't eat citrate because E. coli don't express the right protein to absorb citrate molecules.

To decipher the responsible mutations, Blount worked with Richard Lenski, MSU Hannah Distinguished Professor of Microbiology and Molecular Genetics. Lenski's long-term experiment, cultivating cultures of fast-growing E. coli, was launched in 1988 and has allowed him and his teammates to study more than more than 56,000 generations of bacterial evolution.

The experiment demonstrates natural selection at work. And because samples are frozen and available for later study, when something new emerges scientists can go back to earlier generations to look for the steps that happened along the way.

"We first saw the citrate-using bacteria around 33,000 generations," Lenski explained. "But Zack was able to show that some of the important mutations had already occurred before then by replaying evolution from different intermediate stages. He showed you could re-evolve the citrate-eaters, but only after some of the other pieces of the puzzle were in place."

In the Nature paper, Blount and his teammates analyzed 29 genomes from different generations to find the mutational pieces of the puzzle. They uncovered a three-step process in which the bacteria developed this new ability.

The first stage was potentiation, when the E. coli accumulated at least two mutations that set the stage for later events. The second step, actualization, is when the bacteria first began eating citrate, but only just barely nibbling at it. The final stage, refinement, involved mutations that greatly improved the initially weak function. This allowed the citrate eaters to wolf down their new food source and to become dominant in the population.

"We were particularly excited about the actualization stage," Blount said. "The actual mutation involved is quite complex. It re-arranged part of the bacteria's DNA, making a new regulatory module that had not existed before. This new module causes the production of a protein that allows the bacteria to bring citrate into the cell when oxygen is present. That is a new trick for E. coli."

The change was far from normal, Lenski said.

"It wasn't a typical mutation at all, where just one base-pair, one letter, in the genome is changed," he said. "Instead, part of the genome was copied so that two chunks of DNA were stitched together in a new way. One chunk encoded a protein to get citrate into the cell, and the other chunk caused that protein to be expressed."

Additional co-authors include Jeff Barrick, University of Texas, and Carla Davidson, University of Calgary.

The research was funded in part by the National Science Foundation.

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Journal Reference:

1. Zachary D. Blount, Jeffrey E. Barrick, Carla J. Davidson, Richard E. Lenski. Genomic analysis of a key innovation in an experimental Escherichia coli population. Nature, 2012; DOI: 10.1038/nature11514

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20 Sep, 2012

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Your memory is like the telephone game, altered with each retelling

ScienceDaily (Sep. 19, 2012) — Remember the telephone game where people take turns whispering a message into the ear of the next person in line? By the time the last person speaks it out loud, the message has radically changed. It's been altered with each retelling.

Turns out your memory is a lot like the telephone game, according to a new Northwestern Medicine study.

Every time you remember an event from the past, your brain networks change in ways that can alter the later recall of the event. Thus, the next time you remember it, you might recall not the original event but what you remembered the previous time. The Northwestern study is the first to show this.

"A memory is not simply an image produced by time traveling back to the original event -- it can be an image that is somewhat distorted because of the prior times you remembered it," said Donna Bridge, a postdoctoral fellow at Northwestern University Feinberg School of Medicine and lead author of the paper on the study recently published in the Journal of Neuroscience. "Your memory of an event can grow less precise even to the point of being totally false with each retrieval."

Bridge did the research while she was a doctoral student in lab of Ken Paller, a professor of psychology at Northwestern in the Weinberg College of Arts and Sciences.

The findings have implications for witnesses giving testimony in criminal trials, Bridge noted.

"Maybe a witness remembers something fairly accurately the first time because his memories aren't that distorted," she said. "After that it keeps going downhill."

The published study reports on Bridge's work with 12 participants, but she has run several variations of the study with a total of 70 people. "Every single person has shown this effect," she said. "It's really huge."

"When someone tells me they are sure they remember exactly the way something happened, I just laugh," Bridge said.

The reason for the distortion, Bridge said, is the fact that human memories are always adapting.

"Memories aren't static," she noted. "If you remember something in the context of a new environment and time, or if you are even in a different mood, your memories might integrate the new information."

For the study, people were asked to recall the location of objects on a grid in three sessions over three consecutive days. On the first day during a two-hour session, participants learned a series of 180 unique object-location associations on a computer screen. The next day in session two, participants were given a recall test in which they viewed a subset of those objects individually in a central location on the grid and were asked to move them to their original location. Then the following day in session three, participants returned for a final recall test.

The results showed improved recall accuracy on the final test for objects that were tested on day two compared to those not tested on day two. However, people never recalled exactly the right location. Most importantly, in session three they tended to place the object closer to the incorrect location they recalled during day two rather than the correct location from day one.

"Our findings show that incorrect recollection of the object's location on day two influenced how people remembered the object's location on day three," Bridge explained. "Retrieving the memory didn't simply reinforce the original association. Rather, it altered memory storage to reinforce the location that was recalled at session two."

Bridge's findings also were supported when she measured participants' neural signals --the electrical activity of the brain -- during session two. She wanted to see if the neural signals during session two predicted anything about how people remembered the object's location during session three.

The results revealed a particular electrical signal when people were recalling an object location during session two. This signal was greater when -- the next day -- the object was placed close to that location recalled during session two. When the electrical signal was weaker, recall of the object location was likely to be less distorted.

"The strong signal seems to indicate that a new memory was being laid down," Bridge said, "and the new memory caused a bias to make the same mistake again."

"This study shows how memories normally change over time, sometimes becoming distorted," Paller noted. "When you think back to an event that happened to you long ago -- say your first day at school -- you actually may be recalling information you retrieved about that event at some later time, not the original event."

The research was supported by National Science Foundation grant BCS1025697 and National Institute of Neurological Disorders and Stroke of the National Institutes of Health grant T32 NS047987.

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The above story is reprinted from materials provided by Northwestern University. The original article was written by Marla Paul.

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Journal Reference:

1. D. J. Bridge, K. A. Paller. Neural Correlates of Reactivation and Retrieval-Induced Distortion. Journal of Neuroscience, 2012; 32 (35): 12144 DOI: 10.1523/JNEUROSCI.1378-12.2012

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Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

20 Sep, 2012

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Warming ocean could start big shift of Antarctic ice

ScienceDaily (Sep. 19, 2012) — Fast-flowing and narrow glaciers have the potential to trigger massive changes in the Antarctic ice sheet and contribute to rapid ice-sheet decay and sea-level rise, a new study has found.

Research results published in the journal Proceedings of the National Academy of Sciences reveal in more detail than ever before how warming waters in the Southern Ocean are connected intimately with the movement of massive ice-sheets deep in the Antarctic interior.

"It has long been known that narrow glaciers on the edge of the Antarctica act as discrete arteries termed ice streams, draining the interior of the ice sheet," says Dr Chris Fogwill, an author of the study and an ARC Future Fellow with the UNSW Climate Change Research Centre.

"However, our results have confirmed recent observations suggesting that ocean warming can trigger increased flow of ice through these narrow corridors. This can cause inland sectors of the ice-sheet -- some larger than the state of Victoria -- to become thinner and flow faster."

The researchers, led by Dr Nicholas Golledge from Victoria University of Wellington, New Zealand, tested high-resolution model simulations against reconstructions of the Antarctic ice sheet from 20,000 years ago, during the last glacial maximum.

They used a new model, capable of resolving responses to ice-streams and other fine- scale dynamic features that interact over the entire ice sheet. This had not previously been possible with existing models. They then used this data to analyze the effects of a warming ocean over time.

The results showed that while glacier acceleration triggered by ocean warming is relatively localized, the extent of the resultant ice-sheet thinning is far more widespread. This observation is particularly important in light of recently observed dynamic changes at the margins of Antarctica. It also highlighted areas that are more susceptible than others to changes in ocean temperatures.

The glaciers that responded most rapidly to warming oceans were found in the Weddell Sea, the Admundsen Sea, the central Ross Sea and in the Amery Trough.

The finding is important because of the enormous scale and potential impact the Antarctic ice sheets could have on sea-level rise if they shift rapidly, says Fogwill. "To get a sense of the scale, the Antarctic ice sheet is 3km deep -- three times the height of the Blue Mountains in many areas -- and it extends across an area that is equivalent to the distance between Perth and Sydney.

"Despite its potential impact, Antarctica's effect on future sea level was not fully included in the last IPCC report because there was insufficient information about the behavior of the ice sheet. This research changes that. This new, high-resolution modelling approach will be critical to improving future predictions of Antarctica's contribution to sea level over the coming century and beyond."

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The above story is reprinted from materials provided by University of New South Wales. The original article was written by Alvin Stone.

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Journal Reference:

1. N. R. Golledge, C. J. Fogwill, A. N. Mackintosh, K. M. Buckley. Dynamics of the last glacial maximum Antarctic ice-sheet and its response to ocean forcing. Proceedings of the National Academy of Sciences, 2012; DOI: 10.1073/pnas.1205385109

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19 Sep, 2012

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Out of this world nanoscience: A computer chip that can assemble itself?

ScienceDaily (Sep. 19, 2012) — Imagine a computer chip that can assemble itself. According to Eric M. Furst, professor of chemical and biomolecular engineering at the University of Delaware, engineers and scientists are closer to making this and other scalable forms of nanotechnology a reality as a result of new milestones in using nanoparticles as building blocks in functional materials.

Furst and his postdoctoral researchers, James Swan and Paula Vasquez, along with colleagues at NASA, the European Space Agency, Zin Technologies and Lehigh University, reported the finding Sept. 17 in an article in the Proceedings of the National Academy of Sciences (PNAS) online edition.

The article details how the research team's exploration of colloids, microscopic particles that are mere hundredths the diameter of a human hair, to better understand how nano-"building blocks" can be directed to "self-assemble" into specific structures.

The research team studied paramagnetic colloids while periodically applying an external magnetic field at different intervals. With just the right frequency and field strength, the team was able to watch the particles transition from a random, solid like material into highly organized crystalline structures or lattices.

According to Furst, a professor in UD's Department of Chemical and Biomolecular Engineering, no one before has ever witnessed this guided "phase separation" of particles.

"This development is exciting because it provides insight into how researchers can build organized structures, crystals of particles, using directing fields and it may prompt new discoveries into how we can get materials to organize themselves," Furst said.

Because gravity plays a role in how the particles assemble or disassemble, the research team studied the suspensions aboard the International Space Station (ISS) through collaborative efforts with NASA scientists and astronauts. One interesting observation, Furst reported, was how the structure formed by the particles slowly coarsened, then rapidly grew and separated -- similar to the way oil and water separate when combined -- before realigning into a crystalline structure.

Already, Furst's lab has created novel nanomaterials for use in optical communications materials and thermal barrier coatings. This new detail, along with other recorded data about the process, will now enable scientists to discover other paths to manipulate and create new nanomaterials from nanoparticle building blocks.

"Now, when we have a particle that responds to an electric field, we can use these principles to guide that assembly into structures with useful properties, such as in photonics," Furst added.

The work could potentially prove important in manufacturing, where the ability to pre-program and direct the self-assembly of functional materials is highly desired.

"This is the first time we've presented the relationship between an initially disordered structure and a highly organized one and at least one of the paths between the two. We're excited because we believe the concept of directed self-assembly will enable a scalable form of nanotechnology," he said.

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The above story is reprinted from materials provided by University of Delaware. The original article was written by Karen B. Roberts.

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Journal Reference:

1. J. W. Swan, P. A. Vasquez, P. A. Whitson, E. M. Fincke, K. Wakata, S. H. Magnus, F. D. Winne, M. R. Barratt, J. H. Agui, R. D. Green, N. R. Hall, D. Y. Bohman, C. T. Bunnell, A. P. Gast, E. M. Furst. Multi-scale kinetics of a field-directed colloidal phase transition. Proceedings of the National Academy of Sciences, 2012; DOI: 10.1073/pnas.1206915109

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19 Sep, 2012

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Did a 'forgotten' meteor have a deadly, icy double-punch?

ScienceDaily (Sep. 19, 2012) — When a huge meteor collided with Earth about 2.5 million years ago and fell into the southern Pacific Ocean it not only could have generated a massive tsunami but also may have plunged the world into the Ice Ages, a new study suggests.

A team of Australian researchers says that because the Eltanin meteor -- which was up to two kilometres across -- crashed into deep water, most scientists have not adequately considered either its potential for immediate catastrophic impacts on coastlines around the Pacific rim or its capacity to destabilise the entire planet's climate system.

"This is the only known deep-ocean impact event on the planet and it's largely been forgotten because there's no obvious giant crater to investigate, as there would have been if it had hit a landmass," says Professor James Goff, lead author of a forthcoming paper in the Journal of Quaternary Science. Goff is co-director of UNSW's Australia-Pacific Tsunami Research Centre and Natural Hazards Research Laboratory.

"But consider that we're talking about something the size of a small mountain crashing at very high speed into very deep ocean, between Chile and Antarctica. Unlike a land impact, where the energy of the collision is largely absorbed locally, this would have generated an incredible splash with waves literally hundreds of metres high near the impact site.

"Some modelling suggests that the ensuing mega-tsunami could have been unimaginably large -- sweeping across vast areas of the Pacific and engulfing coastlines far inland. But it also would have ejected massive amounts of water vapour, sulphur and dust up into the stratosphere.

"The tsunami alone would have been devastating enough in the short term, but all that material shot so high into the atmosphere could have been enough to dim the sun and dramatically reduce surface temperatures. Earth was already in a gradual cooling phase, so this might have been enough to rapidly accelerate and accentuate the process and kick start the Ice Ages."

In the paper, Goff and colleagues from UNSW and the Australian Nuclear Science and Technology Organisation, note that geologists and climatologists have interpreted geological deposits in Chile, Antarctica, Australia, and elsewhere as evidence of climatic change, marking the start of the Quaternary period. An alternative interpretation is that some or all of these deposits may be the result of mega-tsunami inundation, the study suggests.

"There's no doubt the world was already cooling through the mid and late Pliocene," says co-author Professor Mike Archer. "What we're suggesting is that the Eltanin impact may have rammed this slow-moving change forward in an instant -- hurtling the world into the cycle of glaciations that characterized the next 2.5 million years and triggered our own evolution as a species.

"As a 'cene' changer -- that is, from the Pliocene to Pleistocene -- Eltanin may have been overall as significant as the meteor that took out the non-flying dinosaurs 65 million years ago. We're urging our colleagues to carefully reconsider conventional interpretations of the sediments we're flagging and consider whether these could be instead the result of a mega-tsunami triggered by a meteor."

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The above story is reprinted from materials provided by University of New South Wales. The original article was written by Bob Beale.

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Journal Reference:

1. James Goff, Catherine Chagué-Goff, Michael Archer, Dale Dominey-Howes, Chris Turney. The Eltanin asteroid impact: possible South Pacific palaeomegatsunami footprint and potential implications for the Pliocene-Pleistocene transition. Journal of Quaternary Science, 2012; DOI: 10.1002/jqs.2571

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19 Sep, 2012

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Fireworks in the early universe

ScienceDaily (Sep. 19, 2012) — Galaxies in the early universe grew fast by rapidly making new stars. Such prodigious star formation episodes, characterized by the intense radiation of the newborn stars, were often accompanied by fireworks in the form of energy bursts caused by the massive central black hole accretion in these galaxies.

This discovery by a group of astronomers led by Peter Barthel of the Kapteyn Institute of the University of Groningen in the Netherlands is published September 19 in the Astrophysical Journal Letters.

Our Milky Way galaxy forms stars at a slow, steady pace: on average one new star a year is born. Since the Milky Way contains about a hundred billion stars, the actual changes are very slight. The Milky Way is an extremely quiet galaxy; its central black hole is inactive, with only weak energy outbursts due to the occasional capture of a passing star or gas cloud.

Bright, exotic radiation

This is in marked contrast to the 'active' galaxies of which there are various types and which were abundant in the early universe. Quasars and radio galaxies are prime examples: owing to their bright, exotic radiation, these objects can be observed as far as the edge of the observable universe. The light of the normal stars in their galaxies is extremely faint at such distances, but active galaxies can be easily detected through their luminous radio, ultraviolet or X-ray radiation, which results from steady accretion onto their massive central black holes.

Peculiar exotic objects

Until recently these distant active galaxies were only interesting in their own right as peculiar exotic objects. Little was known about the composition of their galaxies, or their relationship to the normal galaxy population. However, in 2009 ESA's Herschel space telescope was launched. Herschel is considerably larger than NASA's Hubble, and operates at far-infrared wavelengths. This enables Herschel to detect heat radiation generated by the processes involved in the formation of stars and planets at a small scale, and of complete galaxies at a large scale.

Initial inspection

Peter Barthel has been involved with Herschel since 1997 and heads an observational programme targeting distant quasars and radio galaxies. His team used the Herschel cameras to observe seventy of these objects. Initial inspection of the observations has revealed that many emit bright far-infrared radiation.

The Astrophysical Journal Letter 'Extreme host galaxy growth in powerful early-epoch radio galaxies', by Peter Barthel and co-authors Martin Haas (Bochum University, GER), Christian Leipski (Max-Planck Institute for Astronomy, Heidelberg, GER) and Belinda Wilkes (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), describes their project and the detailed analysis of the first three distant radio galaxies.

Simultaneous grow

The fact that these three objects, as well as many others from the observational sample, emit strong far-infrared radiation indicates that vigorous star formation is taking place in their galaxies, creating hundreds of stars per year during one or more episodes lasting millions of years. The bright radio emission implies strong, simultaneous black hole accretion. This means that while the black holes in the centres of the galaxies are growing (as a consequence of the accretion), the host galaxies are also growing rapidly.

The Herschel observations thereby provide an explanation for the observation that more massive galaxies have more massive black holes. Astronomers have observed this scaling relationship since the 1990s: the fireworks in the early universe could well be responsible for this relationship.

Barthel: 'It is becoming clear that active galaxies are not only among the largest, most distant, most powerful and most spectacular objects in the universe, but also among the most important objects; many if not all massive normal galaxies must also have gone through similar phases of simultaneous black hole-driven activity and star formation.'

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The above story is reprinted from materials provided by University of Groningen.

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Journal Reference:

1. Peter Barthel, Martin Haas, Christian Leipski, Belinda Wilkes. EXTREME HOST GALAXY GROWTH IN POWERFUL EARLY-EPOCH RADIO GALAXIES. The Astrophysical Journal, 2012; 757 (2): L26 DOI: 10.1088/2041-8205/757/2/L26

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19 Sep, 2012

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Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/top_science/~3/XsAyJM_aQ6k/120919082931.htm
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Evolutionary history of lizards and snakes reconstructed using massive molecular dataset

ScienceDaily (Sep. 18, 2012) — A new study, published online in Biology Letters on Sept. 19, has utilized a massive molecular dataset to reconstruct the evolutionary history of lizards and snakes. The results reveal a surprising finding about the evolution of snakes: that most snakes we see living on the surface today arose from ancestors that lived underground.

The article, entitled "Resolving the phylogeny of lizards and snakes (Squamata) with extensive sampling of genes and species," describes research led by John J. Wiens, an Associate Professor in the Department of Ecology and Evolution at Stony Brook University. The study was based on 44 genes and 161 species of lizards and snakes, one of the largest genetic datasets assembled for reptiles.

The results show that almost all groups of snakes arose from within a bizarre group of burrowing blind snakes called scolecophidians. This finding implies that snakes ancestrally lived underground, and that the thousands of snake species living today on the surface evolved from these subterranean ancestors.

The authors suggest that there are still traces of this subterranean ancestry in the anatomy of surface-dwelling snakes. "For example, no matter where they live, snakes have an elongate body and a relatively short tail, and outside of snakes, this body shape is only found in lizards that live underground," said Professor Wiens. "Snakes have kept this same basic body shape as they have evolved to invade nearly every habitat on the planet -- from rainforest canopies to deserts and even the oceans."

Co-authors of the study include Carl R. Hutter, Daniel G. Mulcahy, Brice P. Noonan, Ted M. Townsend, Jack W. Sites Jr., and Tod W. Reeder. The work was performed at Stony Brook University, Brigham Young University, and San Diego State University.

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The above story is reprinted from materials provided by Stony Brook University.

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Journal Reference:

1. J. J. Wiens, C. R. Hutter, D. G. Mulcahy, B. P. Noonan, T. M. Townsend, J. W. Sites, T. W. Reeder. Resolving the phylogeny of lizards and snakes (Squamata) with extensive sampling of genes and species. Biology Letters, 2012; DOI: 10.1098/rsbl.2012.0703

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19 Sep, 2012

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Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/top_science/~3/iRDhWGVfsCk/120919081834.htm
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Crews uncover massive Roman mosaic in southern Turkey

ScienceDaily (Sep. 18, 2012) — A University of Nebraska-Lincoln archaeological team has uncovered a massive Roman mosaic in southern Turkey -- a meticulously crafted, 1,600-square-foot work of decorative handiwork built during the region's imperial zenith.

It's believed to be the largest mosaic of its type in the region and demonstrates the reach and cultural influence of the Roman Empire in the area in the third and fourth centuries A.D., said Michael Hoff, Hixson-Lied professor of art history at UNL and the director of the excavation.

"Its large size signals, in no small part, that the outward signs of the empire were very strong in this far-flung area," Hoff said. "We were surprised to have found a mosaic of such size and of such caliber in this region -- it's an area that had usually been off the radar screens of most ancient historians and archeologists, and suddenly this mosaic comes into view and causes us to change our focus about what we think (the region) was like in antiquity."

Since 2005, Hoff's team has been excavating the remains of the ancient city of Antiochia ad Cragum on the southern Turkish coast. Antiochus of Commagene, a client-king of Rome, founded the city in the middle of the first century.

"This region is not well understood in terms of history and archaeology," Hoff said. "It's not a place in which archaeologists have spent a lot of time, so everything we find adds more evidence to our understanding of this area of the Roman Empire.

"We're beginning to understand now that it was more Romanized, more in line with the rest of the Roman world than was suspected before. (The nature of the mosaic) hammers home how Roman this city truly is."

Antiochia ad Cragum had many of the trappings expected of a Roman provincial city -- temples, baths, markets and colonnaded streets, said Hoff. The city thrived during the empire from an economy focused on agricultural products, especially wine and lumber.

Excavation has focused on a third-century imperial temple, and also a street lined with shops. In July, the team began to explore the mosaic, which was part of a Roman bath. The decoration consists of large squares, each filled with different colored geometric designs and ornamentation.

"This would have been a very formal associated pavement attached to the bath," Hoff said. "This is a gorgeous mosaic, and its size is unprecedented" -- so large, in fact, that work crews have uncovered only an estimated 40 percent of its total area.

Hoff said it appears the mosaic served as a forecourt for the adjacent large bath, and that at least on one side, evidence shows there was a roof covering the geometric squares that would have been supported by piers. Those piers' remains are preserved, he said.

Meanwhile, the middle of the mosaic was outfitted with a marble-lined, 25-foot-long pool, which would have been uncovered and open to the sun. The other half of the mosaic adjacent to the bath is expected to contain similar decoration, Hoff said. Crews expect to unearth the entire work next summer.

Team members first noticed the mosaic in 2001 when a large archaeological survey project that included Hoff noticed a local farmer had plowed up pieces of a mosaic in a field next to a still-standing bath structure. The find was brought to the attention of the archeological museum in Alanya, which two years later made a minor investigation that revealed a small portion of the mosaic.

Last year, the museum invited Hoff to clear the mosaic and to preserve it for tourists and scholars. Hoff's 60-person team also included Birol Can, assistant professor of archaeology at Atatürk University in Ezrurum, Turkey, a sister university to the University of Nebraska; students from UNL; other students from Turkey and the United States; and workers from a nearby village. About 35 students participated in the project as part of a summer field school Hoff runs.

Phalin Strong, a sophomore art major from Lincoln, said the work was difficult but satisfying.

"It is strange to realize that you are the first person to see this for centuries -- a feeling that also made me think about impermanence and what importance my actions have on humanity and history," Strong said.

Ben Kreimer, a senior journalism major, agreed: "(Working on) the mosaic was great because the more soil you removed, the more mosaic there was," he said. "Visually, it was also stunning, especially once it got cleaned off. It wasn't very deep under the surface of the soil, either, so … we had to be careful not to swing the handpick too hard so as not to damage the priceless mosaic that lay just inches beneath us."

Hoff said the significance of this summer's discovery has him eager to return to the site and see what the rest of the excavation uncovers.

"As an archaeologist, I am always excited to make new discoveries. The fact that this discovery is so large and also not completely uncovered makes it doubly exciting," he said. "I am already looking forward to next year, though I just returned from Turkey."

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The above story is reprinted from materials provided by University of Nebraska-Lincoln. The original article was written by Kathe Andersen and Steve Smith.

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18 Sep, 2012

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Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/top_science/~3/XqPKwkji0UY/120918083903.htm
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