Observations of gamma-ray burst reveal surprising ingredients of early galaxies

ScienceDaily (Nov. 2, 2011) — An international team of astronomers led by the Max Planck Institute for Extraterrestrial Physics has used the brief but brilliant light of a distant gamma-ray burst as a probe to study the make-up of very distant galaxies. Surprisingly the new observations revealed two galaxies in the young Universe that are richer in the heavier chemical elements than the Sun. The two galaxies may be in the process of merging. Such events in the early Universe will drive the formation of many new stars and may be the trigger for gamma-ray bursts.

Gamma-ray bursts are the brightest explosions in the Universe. They are first spotted by orbiting observatories that detect the initial short burst of gamma rays. After their positions have been pinned down, they are then immediately studied using large ground-based telescopes that can detect the visible-light and infrared afterglows that the bursts emit over the succeeding hours and days. One such burst, called GRB 090323, was first spotted by the NASA Fermi Gamma-ray Space Telescope. Very soon afterwards it was picked up by the X-ray detector on NASA's Swift satellite and with the GROND system at the MPG/ESO 2.2-metre telescope in Chile. From the GROND observations, the astronomers estimated the minimum rate of star formation, which has to be several times higher than the one in our Galaxy. They could, however, only determine a minimum value because the detected emission could be heavily affected (i.e. absorbed) by the presence of dust in the galaxies. The real rate of star formation, once the (unknown) dust absorption has been taken into account, could easily be 50 times higher than in the Milky Way.

The burst was also studied in great detail using ESO's Very Large Telescope (VLT) just one day after it exploded. These observations show that the brilliant light from the gamma-ray burst had passed through its own host galaxy and another galaxy nearby. These galaxies are being seen as they were about 12 billion years ago. Such distant galaxies are very rarely caught in the glare of a gamma-ray burst.

"When we studied the light from this gamma-ray burst we didn't know what we might find. It was a surprise that the cool gas in these two galaxies in the early Universe proved to have such an unexpected chemical make-up," explains Sandra Savaglio (Max-Planck Institute for Extraterrestrial Physics, Garching, Germany), lead author of the paper describing the new results. "These galaxies have more heavy elements than have ever been seen in a galaxy so early in the evolution of the Universe. We didn't expect the Universe to be so mature, so chemically evolved, so early on."

As light from the gamma-ray burst passed through the galaxies, the gas there acted like a filter, and absorbed some of the light from the gamma-ray burst at certain wavelengths. Without the gamma-ray burst these faint galaxies would be invisible. By carefully analysing the tell-tale fingerprints from different chemical elements the team was able to work out the composition of the cool gas in these very distant galaxies, and in particular how rich they were in heavy elements.

It is expected that galaxies in the young Universe will be found to contain smaller amounts of heavier elements than galaxies at the present day, such as the Milky Way. The heavier elements are produced during the lives and deaths of generations of stars, gradually enriching the gas in the galaxies. Astronomers can use the chemical enrichment in galaxies to indicate how far they are through their lives. But the new observations, surprisingly, revealed that some galaxies were already very rich in heavy elements less than two billion years after the Big Bang. Something unthinkable until recently.

The newly discovered pair of young galaxies must be forming new stars at a tremendous rate, to enrich the cool gas so strongly and quickly. As the two galaxies are close to each other they may be in the process of merging, which would also provoke star formation when the gas clouds collide. The new results also support the idea that gamma-ray bursts may be associated with vigorous massive star formation.

Energetic star formation in galaxies like these might have ceased early on in the history of the Universe. Twelve billion years later, at the present time, the remains of such galaxies would contain a large number of stellar remnants such as black holes and cool dwarf stars, forming a hard to detect population of "dead galaxies," just faint shadows of how they were in their brilliant youths. Finding such corpses in the present day would be a challenge.

"We were very lucky to observe GRB 090323 when it was still sufficiently bright, so that it was possible to obtain spectacularly detailed observations with the VLT. Gamma-ray bursts only stay bright for a very short time and getting good quality data is very hard. We hope to observe these galaxies again in the future when we have much more sensitive instruments, they would make perfect targets for the E-ELT," concludes Savaglio.

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The above story is reprinted from materials provided by Max-Planck-Institut für extraterrestrische Physik (MPE).

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Journal Reference:

S. Savaglio et al. Super-solar Metal Abundances in Two Galaxies at z~3.57 revealed by the GRB090323 Afterglow Spectrum. Monthly Notices of the Royal Astronomical Society, 2011

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Simple compound with surprising antifreeze properties

ScienceDaily (Oct. 25, 2011) — A chemical compound used to stabilize particles in suspension has proved capable of controlling the growth of ice crystals. This finding was made by CNRS/Saint-Gobain researchers, in collaboration with CNRS-affiliated teams at INSA Lyon and Université Claude Bernard Lyon 1. Surprisingly, the compound in question is a simple molecule, not at all like the macromolecules previously known for their antifreeze properties. It offers many advantages, including low production costs, stability and ease of use, which should open the way to industrial applications.

Published in the online journal PLoS ONE, this work also provides new leads for the development of synthetic equivalents of antifreeze proteins, different from those currently produced.

The formation of ice crystals can have multiple, and often destructive, consequences. Cell degradation in living organisms, damage to land and roads in cold climates, ice crystals in ice creams… These are all examples of situations where it is useful to control ice growth. Many organisms and species that live in cold environments have adapted to control ice growth. Their resistance to low temperatures is based on the presence of antifreeze proteins, all of which are made up of very long organic chains with amphiphilic structures (partly hydrophilic, partly hydrophobic). How do these proteins interact with ice crystals? Researchers are trying to identify the mechanism enabling antifreeze proteins to identify these crystals, but the phenomenon is still not fully understood. In addition, since these proteins are extremely costly to extract, the preferred solution is to create synthetic equivalents inspired by natural structures. All proteins currently known for their "antifreeze" properties are macromolecules (like glycoproteins, polysaccharides, etc.).

A team led by Sylvain Deville(1), CNRS researcher at the LSFC (Laboratoire de Synthèse et Fonctionnalisation des Céramiques, Synthesis and Functionalization of Ceramics Laboratory, CNRS/Saint-Gobain), in collaboration with the Matériaux, Ingénierie et Sciences (Materials, Engineering and Sciences) laboratory (CNRS/INSA Lyon / Université Claude Bernard Lyon 1), has discovered that zirconium acetate, a chemical compound normally used to stabilize particles in suspension, can control ice crystal growth. The compound governs the morphology of the ice crystals obtained by freezing a solution in which it is combined with water. The crystals obtained when adding zirconium acetate are very homogenous, whereas those obtained without it show no particular uniformity.

These results are quite surprising, given that zirconium acetate is a "salt,"(2) a simple compound that is radically different from the macromolecules known for their antifreeze properties. It was not known as a substance capable of controlling ice crystal growth. Such control can be exerted in a number of ways: by reducing the speed of crystal growth (to slow their formation), by lowering the freezing point (to delay their formation), or by controlling their morphology, as in this case. Since this implies a direct interaction with the ice crystals, the researchers were surprised to find out that such radically different molecules as zirconium acetate and proteins could affect crystalline growth.

This compound offers significant advantages over existing equivalents, whether natural or synthetic. It is cheap to produce, stable, "simple" and easy to use, which bodes well for a wealth of future industrial applications. In addition, since it is totally different from all previously identified and/or developed substances with the same function, further research could lead to the development of other molecules with antifreeze properties.

This project relied on X-ray diffraction and imaging. These works were made possible by using the X-ray synchrotron (beam line ID19) at the ESRF in Grenoble, France. They are covered by two patents published on October 1, 2011.

Notes:

Laureate of an ERC Junior grant in 2011.In chemistry, a salt is an ionic compound made up of cations and anions, forming a neutral product with no net charge. This type of salt is much different from edible (table) salt.

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The above story is reprinted from materials provided by CNRS (Délégation Paris Michel-Ange), via AlphaGalileo.

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Journal Reference:

Sylvain Deville, Céline Viazzi, Jérôme Leloup, Audrey Lasalle, Christian Guizard, Eric Maire, Jérôme Adrien, Laurent Gremillard. Ice Shaping Properties, Similar to That of Antifreeze Proteins, of a Zirconium Acetate Complex. PLoS ONE, 2011; 6 (10): e26474 DOI: 10.1371/journal.pone.0026474

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Pendulums and floating film: Two seemingly unrelated phenomena share surprising link

ScienceDaily (Oct. 11, 2011) — A coupled line of swinging pendulums apparently has nothing in common with an elastic film that buckles and folds under compression while floating on a liquid, but scientists at the University of Chicago and Tel Aviv University have discovered a deep connection between the two phenomena.

Energy carried in ordinary waves, like those seen on the ocean near a beach, quickly disperses. But the energy in the coupled pendulums and in compressed elastic film concentrates into different kinds of waves, ones with discrete packets of energy called "solitons."

Solitons express themselves in other realms as well. In telecommunications, for example, pulsing light travels as solitons through optical fibers. "What is special about solitons, and this very special way of localizing energy, is that it does not disperse," said Haim Diamant, associate professor of chemistry at Tel Aviv University. "It remains a very well-defined, focused packet."

The connection, which Diamant and UChicago's Thomas Witten report Oct. 14 in the journal Physical Review Letters, is subtle and more easily appreciated in visual form (see graphic). Witten graphed the swing angle of the pendulums as time progresses. Then he made a curve whose angle with the horizontal varies to match the swing angles along the diagonal edge of the graph. The resulting curve takes the same shape as the profile of a folded elastic film floating on a liquid, like the film shown at the bottom of the picture.

Witten and Diamant began collaborating while the latter worked at UChicago's James Franck Institute as a postdoctoral scientist from 1999 to 2002. They have been working together on puzzles emerging from the laboratory of another collaborator, Ka Yee Lee, UChicago professor in chemistry, ever since. Lee's research group studies the complex mixture of lipids and proteins that lines the sacs of the lung. These molecular linings fold and unfold as we inhale and exhale; the folding appears important for normal breathing.

Slowly growing energy

The energy applied to the film's deformation starts out weak, then grows stronger. Once the wrinkling energy in the film grows stronger, it concentrates itself into a fold shaped like the folding curve in the image.

Though the fold appears in a specific place on the film, "the motion resulting from folding extends over a big region. Usually big things are slow," said Witten, the Homer J. Livingston Professor in Physics. "But this is a big thing that is not slow. It's a rapid jerk, and we want to see what enables such rapid, large-scale motion."

Lee and her associates aim to understand breathing mechanics using synthetic films only one layer of molecules thick to simulate the surfactant that lines the microscopic air sacs found in the lungs. Diamant and Witten sought to solve the equation that exactly describes the fold shape of such a film. They knew it would be a difficult task, given that it was a nonlinear equation, one in which simple changes produce complicated effects.

A typical nonlinear problem might absorb decades of work without yielding a solution; this one seemed different. "There were strange hints that told us this problem might be solved exactly," Diamant said. "It's very rare that a nonlinear problem can be solved exactly."

Miracle solution

These hints had appeared in numerical simulations of the folding process generated by Enrique Cerda, a collaborator at the University of Santiago in Chile. "It was a miracle that we found an exact solution, but we had a strong feeling that it existed," Diamant said.

Once Diamant and Witten solved the problem, they realized that the solution resembled the sine-Gordon equation, well-known among mathematicians and physicists, which describes how a coupled line of swinging pendulums concentrate their energy.

Their resulting paper lays out the first example the authors know of in which soliton motion of a dynamical system can help scientists understand material deformation. The materials in this instance involve a thin, rigid layer floating on a fluid surface, a structure commonly found in biological tissues and synthetic coatings.

The finding has still-undetermined technological or biomedical applications, but it offers a way to control the film's deformation, including making the fold stick down into or up out of the water, forming a groove.

"This groove is controllable," Witten said. "You can shape the groove; you can make it come; you can make it go away." One also could control the location of the groove on the film, making it possible to manipulate the film on the scale of a few microns -- a fraction the width of a human hair.

"If there was some other material in the water that was attracted to the surface, we could make it nestle into this shape and we could capture it," Witten explained. "We think that this shape could have some potential that people don't realize."

As a next step, Diamant and Witten wonder if the dynamics of swinging pendulums can tell them anything about the dynamics of a folding elastic film. "All we have described at the moment is this static shape of the fold, but folding too is a dynamic phenomenon," Witten said.

Squeeze the film, and it will begin to fold after a period of time. Witten and Diamant would like to further describe how that process works based on what the swinging pendulums do.

"It seems only natural, but things like that are dangerous and they don't necessarily work," Witten noted. "But we do know that there is a lot known about the solitons that we can potentially harness to understand the folds."

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Chicago. The original article was written by Steve Koppes.

Journal Reference:

Haim Diamant, Thomas Witten. Compression Induced Folding of a Sheet: An Integrable System. Physical Review Letters, 2011; 107 (16) DOI: 10.1103/PhysRevLett.107.164302

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Pendulums and floating film: Two seemingly unrelated phenomena share surprising link

ScienceDaily (Oct. 11, 2011) — A coupled line of swinging pendulums apparently has nothing in common with an elastic film that buckles and folds under compression while floating on a liquid, but scientists at the University of Chicago and Tel Aviv University have discovered a deep connection between the two phenomena.

Energy carried in ordinary waves, like those seen on the ocean near a beach, quickly disperses. But the energy in the coupled pendulums and in compressed elastic film concentrates into different kinds of waves, ones with discrete packets of energy called "solitons."

Solitons express themselves in other realms as well. In telecommunications, for example, pulsing light travels as solitons through optical fibers. "What is special about solitons, and this very special way of localizing energy, is that it does not disperse," said Haim Diamant, associate professor of chemistry at Tel Aviv University. "It remains a very well-defined, focused packet."

The connection, which Diamant and UChicago's Thomas Witten report Oct. 14 in the journal Physical Review Letters, is subtle and more easily appreciated in visual form (see graphic). Witten graphed the swing angle of the pendulums as time progresses. Then he made a curve whose angle with the horizontal varies to match the swing angles along the diagonal edge of the graph. The resulting curve takes the same shape as the profile of a folded elastic film floating on a liquid, like the film shown at the bottom of the picture.

Witten and Diamant began collaborating while the latter worked at UChicago's James Franck Institute as a postdoctoral scientist from 1999 to 2002. They have been working together on puzzles emerging from the laboratory of another collaborator, Ka Yee Lee, UChicago professor in chemistry, ever since. Lee's research group studies the complex mixture of lipids and proteins that lines the sacs of the lung. These molecular linings fold and unfold as we inhale and exhale; the folding appears important for normal breathing.

Slowly growing energy

The energy applied to the film's deformation starts out weak, then grows stronger. Once the wrinkling energy in the film grows stronger, it concentrates itself into a fold shaped like the folding curve in the image.

Though the fold appears in a specific place on the film, "the motion resulting from folding extends over a big region. Usually big things are slow," said Witten, the Homer J. Livingston Professor in Physics. "But this is a big thing that is not slow. It's a rapid jerk, and we want to see what enables such rapid, large-scale motion."

Lee and her associates aim to understand breathing mechanics using synthetic films only one layer of molecules thick to simulate the surfactant that lines the microscopic air sacs found in the lungs. Diamant and Witten sought to solve the equation that exactly describes the fold shape of such a film. They knew it would be a difficult task, given that it was a nonlinear equation, one in which simple changes produce complicated effects.

A typical nonlinear problem might absorb decades of work without yielding a solution; this one seemed different. "There were strange hints that told us this problem might be solved exactly," Diamant said. "It's very rare that a nonlinear problem can be solved exactly."

Miracle solution

These hints had appeared in numerical simulations of the folding process generated by Enrique Cerda, a collaborator at the University of Santiago in Chile. "It was a miracle that we found an exact solution, but we had a strong feeling that it existed," Diamant said.

Once Diamant and Witten solved the problem, they realized that the solution resembled the sine-Gordon equation, well-known among mathematicians and physicists, which describes how a coupled line of swinging pendulums concentrate their energy.

Their resulting paper lays out the first example the authors know of in which soliton motion of a dynamical system can help scientists understand material deformation. The materials in this instance involve a thin, rigid layer floating on a fluid surface, a structure commonly found in biological tissues and synthetic coatings.

The finding has still-undetermined technological or biomedical applications, but it offers a way to control the film's deformation, including making the fold stick down into or up out of the water, forming a groove.

"This groove is controllable," Witten said. "You can shape the groove; you can make it come; you can make it go away." One also could control the location of the groove on the film, making it possible to manipulate the film on the scale of a few microns -- a fraction the width of a human hair.

"If there was some other material in the water that was attracted to the surface, we could make it nestle into this shape and we could capture it," Witten explained. "We think that this shape could have some potential that people don't realize."

As a next step, Diamant and Witten wonder if the dynamics of swinging pendulums can tell them anything about the dynamics of a folding elastic film. "All we have described at the moment is this static shape of the fold, but folding too is a dynamic phenomenon," Witten said.

Squeeze the film, and it will begin to fold after a period of time. Witten and Diamant would like to further describe how that process works based on what the swinging pendulums do.

"It seems only natural, but things like that are dangerous and they don't necessarily work," Witten noted. "But we do know that there is a lot known about the solitons that we can potentially harness to understand the folds."

Recommend this story on Facebook, Twitter,
and Google +1:

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Chicago. The original article was written by Steve Koppes.

Journal Reference:

Haim Diamant, Thomas Witten. Compression Induced Folding of a Sheet: An Integrable System. Physical Review Letters, 2011; 107 (16) DOI: 10.1103/PhysRevLett.107.164302

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here