ScienceDaily (Sep. 1, 2010) — In December 2010, IceCube — the world’s first kilometer-scale neutrino observatory, whiuch is located beneath the Antarctic ice — will finally be completed after two decades of planning. In an article in the AIP’s Review of Scientific Instruments, Francis Halzen, the principal investigator of the IceCube project, and his colleague Spencer Klein of Lawrence Berkeley National Laboratory provide a comprehensive description of the observatory, its instrumentation, and its scientific mission — including its most publicized goal: finding the sources of cosmic rays.

“Almost a century after their discovery, we do not know from where the most energetic particles to hit the Earth originate and how they acquire their incredible energies,” says Halzen, a professor of physics at the University of Wisconsin in Madison.

After light, neutrinos, which are created in the decay of radioactive particles, are the most abundant particles in the universe. High-energy neutrinos are formed in the universe’s most violent events, like exploding stars and gamma ray bursts. Because the neutrino has no charge, essentially no mass, and only interacts weakly with matter, trillions of neutrinos pass through our bodies each day, without effect. On extremely rare occasions, a neutrino will strike the nucleus of an atom, creating a particle, called a muon, and blue light that can be detected with optical sensors. The trick is spying those collisions — and, in particular, the collisions of high-energy neutrinos. IceCube does it by sheer virtue of its size.

At 1 kilometer on a side — with 5,160 optical sensors occupying a gigaton of ice — the observatory is orders of magnitude bigger than other neutrino detectors; the Superkamiokande detector in the Japanese Alps, for example, is only 40 meters on a side.

“IceCube has been totally optimized for size in order to be sensitive to the very small neutrino fluxes that may reveal the sources of cosmic rays and the particle nature of dark matter,” Halzen says.

This work is supported by the National Science Foundation.

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Institute of Physics, via EurekAlert!, a service of AAAS.

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Journal Reference:

1. Francis Halzen, Spencer R. Klein. IceCube: An instrument for neutrino astronomy. Review of Scientific Instruments, 2010; 81 (8): 081101 DOI: 10.1063/1.3480478

ScienceDaily (Aug. 26, 2010) — Astronomers believe they have discovered the origin of our universe’s first super-massive black holes, which formed some 13 billion years ago.

The discovery fills in a missing chapter of our universe’s early history, and could help write the next chapter — in which scientists better understand how gravity and dark matter formed the universe as we know it.

In the journal Nature, Ohio State University astronomer Stelios Kazantzidis and colleagues describe computer simulations in which they modeled the evolution of galaxies and black holes during the first few billion years after the Big Bang.

Our universe is thought to be 14 billion years old. Other astronomers recently determined that big galaxies formed much earlier in the universe’s history than previously thought — within the first 1 billion years, Kazantzidis explained.

These new computer simulations show that the first-ever super-massive black holes were likely born when those early galaxies collided and merged together.

“Our results add a new milestone to the important realization of how structure forms in the universe,” he said.

For more than two decades, the prevailing wisdom among astronomers has been that galaxies evolved hierarchically — that is, gravity drew small bits of matter together first, and those small bits gradually came together to form larger structures.

Kazantzidis and his team turn that notion on its head.

“Together with these other discoveries, our result shows that big structures — both galaxies and massive black holes — build up quickly in the history of the universe,” he said. “Amazingly, this is contrary to hierarchical structure formation.”

The paradox is resolved once one realizes that dark matter grows hierarchically, but ordinary matter doesn’t,” he continued. “The normal matter that makes up visible galaxies and super-massive black holes collapses more efficiently, and this was true also when the universe was very young, giving rise to anti-hierarchical formation of galaxies and black holes.”

For Kazantzidis and other astronomers, our Milky Way galaxy is small compared to others.

So when it comes to normal matter, big bits like giant galaxies and super-massive black holes come together quickly, and smaller bits like our own Milky Way galaxy — and the comparatively small black hole at its center — form more slowly. The galaxies that formed those first super-massive black holes are still around, Kazantzidis added.

“One of them is likely our neighbor in the Virgo Cluster, the elliptical galaxy M87,” he said. “The galaxies we saw in our simulation would be the biggest galaxies known today, about 100 times the size of the Milky Way. M87 fits that description.”

They started their simulations with two giant primordial galaxies — ones made of the kinds of stars that were around at the beginning of the universe. Astronomers believe that back then, all stars would have been much more massive than present-day stars — up to 300 times the mass of our sun.

Then the astronomers simulated the galaxies colliding and merging together.

The astronomers were able to make their discovery because they used supercomputers to provide a high-resolution view of what happened next.

Previous simulations showed details of the merged galaxy down to only about 300 light-years across. A light-year is the distance that light travels in year, about six trillion miles.

These new simulations contained features that were 100 times smaller, and revealed details in the heart of the merged galaxies on a scale of less than a light year.

The astronomers saw two things happen. First, gas and dust in the center of the galaxies condensed to form a tight nuclear disk. Then the disk became unstable, and the gas and dust contracted again, to form an even denser cloud that eventually spawned a super-massive black hole.

The implications for cosmology are far-reaching, Kazantzidis said.

“For example, the standard idea — that a galaxy’s properties and the mass of its central black hole are related because the two grow in parallel — will have to be revised. In our model, the black hole grows much faster than the galaxy. So it could be that the black hole is not regulated at all by the growth of the galaxy. It could be that the galaxy is regulated by the growth of the black hole.”

He and his cohorts also hope that their work will aid astronomers who are searching the skies for direct evidence of Einstein’s theory of general relativity: gravitational waves.

According to general relativity, any ancient galaxy mergers would have created massive gravitational waves — ripples in the space-time continuum — the remnants of which should still be visible today.

New gravitational wave detectors, such as NASA’s Laser Interferometer Space Antenna, were designed to detect these waves directly, and open a new window into astrophysical and physical phenomena that cannot be studied in other ways.

Scientists will need to know how super-massive black holes formed in the early universe and how they are distributed in space today in order interpret the results of those experiments. The new computer simulations should provide a clue.

Coauthors on the Nature paper include Lucio Mayer and Simone Callegari of the Institute for Theoretical Physics at the University of Zürich, and Andres Escala, formerly of Stanford University and now at the Universidad de Chile.

This work was funded by the Swiss National Science Foundation, the Center for Cosmology and Astro-Particle Physics at Ohio State, and the Kavli Institute for Particle Astrophysics at Stanford University. Simulations were performed on the Zbox3 supercomputer at the University of Zürich and on the Brutus cluster at ETH Zürich.

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Ohio State University. The original article was written by Pam Frost Gorder.

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Journal Reference:

1. Mayer et al. Direct formation of supermassive black holes via multi-scale gas inflows in galaxy mergers. Nature, 2010; 466 (7310): 1082 DOI: 10.1038/nature09294

(Sep. 8, 2010) — Seven years ago Northwestern University physicist Adilson E. Motter conjectured that the expansion of the universe at the time of the big bang was highly chaotic. Now he and a colleague have proven it using rigorous mathematical arguments.

The study, published by the journal Communications in Mathematical Physics, reports not only that chaos is absolute but also the mathematical tools that can be used to detect it. When applied to the most accepted model for the evolution of the universe, these tools demonstrate that the early universe was chaotic.

Certain things are absolute. The speed of light, for example, is the same with respect to any observer in the empty space. Others are relative. Think of the pitch of a siren on an ambulance, which goes from high to low as it passes the observer. A longstanding problem in physics has been to determine whether chaos — the phenomenon by which tiny events lead to very large changes in the time evolution of a system, such as the universe — is absolute or relative in systems governed by general relativity, where the time itself is relative.

A concrete aspect of this conundrum concerns one’s ability to determine unambiguously whether the universe as a whole has ever behaved chaotically. If chaos is relative, as suggested by some previous studies, this question simply cannot be answered because different observers, moving with respect to each other, could reach opposite conclusions based on the ticks of their own clocks.

“A competing interpretation has been that chaos could be a property of the observer rather than a property of the system being observed,” said Motter, an author of the paper and an assistant professor of physics and astronomy at Northwestern’s Weinberg College of Arts and Sciences. “Our study shows that different physical observers will necessarily agree on the chaotic nature of the system.”

The work has direct implications for cosmology and shows in particular that the erratic changes between red- and blue-shift directions in the early universe were in fact chaotic.

Motter worked with colleague Katrin Gelfert, a mathematician from the Federal University of Rio de Janeiro, Brazil, and a former visiting faculty member at Northwestern, who says that the mathematical aspects of the problem are inspiring and likely to lead to other mathematical developments.

An important open question in cosmology is to explain why distant parts of the visible universe — including those that are too distant to have ever interacted with each other — are so similar.

“One might suggest ‘Because the large-scale universe was created uniform,’” Motter said, “but this is not the type of answer physicists would take for granted.”

Fifty years ago, physicists believed that the true answer could be in what happened a fraction of a second after the big bang. Though the initial studies failed to show that an arbitrary initial state of the universe would eventually converge to its current form, researchers found something potentially even more interesting: the possibility that the universe as a whole was born inherently chaotic.

The present-day universe is expanding and does so in all directions, Motter explained, leading to red shift of distant light sources in all three dimensions — the optical analog of the low pitch in a moving siren. The early universe, on the other hand, expanded in only two dimensions and contracted in the third dimension.

This led to red shift in two directions and blue shift in one. The contracting direction, however, was not always the same in this system. Instead, it alternated erratically between x, y and z.

“According to the classical theory of general relativity, the early universe experienced infinitely many oscillations between contracting and expanding directions,” Motter said.

“This could mean that the early evolution of the universe, though not necessarily its current state, depended very sensitively on the initial conditions set by the big bang.”

This problem gained a new dimension 22 years ago when two other researchers, Gerson Francisco and George Matsas, found that different descriptions of the same events were leading to different conclusions about the chaotic nature of the early universe. Because different descriptions can represent the perspectives of different observers, this challenged the hypothesis that there would be an agreement among different observers. Within the theory of general relativity, such an agreement goes by the name of a “relativistic invariant.”

“Technically, we have established the conditions under which the indicators of chaos are relativistic invariants,” Motter said. “Our mathematical characterization also explains existing controversial results. They were generated by singularities induced by the choice of the time coordinate, which are not present for physically admissible observables.”

Motter also is an assistant professor of engineering sciences and applied mathematics at the McCormick School of Engineering and Applied Science, a member of the executive committee of the Northwestern Institute on Complex Systems (NICO) and a member of the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA).

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Northwestern University, via EurekAlert!, a service of AAAS.

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Journal Reference:

1. Katrin Gelfert, Adilson E. Motter. (Non)Invariance of Dynamical Quantities for Orbit Equivalent Flows. Communications in Mathematical Physics, 2010; DOI: 10.1007/s00220-010-1120-x

(Sep. 8, 2010) — A group of international astronomers in the UK, France and the USA, led by the University of Leicester, have found proof to confirm the distance and brightness of the most extreme ultra-luminous X-ray source, which may herald a new type of Black Hole.

The X-ray source, HLX-1, is the most extreme member of an extraordinary class of objects — the ultra-luminous X-ray sources — and is located in the galaxy ESO 243-49 at a distance of ~300 million light years from the Earth.

The astronomers’ findings confirm that the extreme luminosity (which is a factor of ~100 above most other objects in its class, and a factor of ~10 higher than the next brightest ultra-luminous X-ray source) is correct.

This is forcing scientists to rethink their theories on the maximum brightness of ultra-luminous X-ray sources, and provides support to the idea that HLX-1 may contain an intermediate mass black hole.

This latest result will be reported September 8 in the scientific journal, The Astrophysical Journal.

Using the European Southern Observatory’s (ESO’s) Very Large Telescope (VLT) in Chile, the team have obtained an optical spectrum of their record breaking ultra-luminous X-ray source (HLX-1) in the distant galaxy ESO 243-49.

Their findings enable them to show conclusively that HLX-1 is indeed located within this galaxy, and is neither a foreground star nor a background galaxy. The main implication of this discovery is that ultra-luminous X-ray sources such as HLX-1 can be brighter than was originally thought, which is consistent with at least the brightest of them hosting intermediate mass black holes.

A black hole is an ultra-dense object with such a powerful gravitational field that it absorbs all the light that passes near it and reflects nothing.

While astrophysicists have suspected that an intermediate class of black hole might exist, with masses between a hundred and several hundred thousand times that of the Sun, such black holes had not previously been reliably detected and their existence has been fiercely debated among the astronomical community.

The VLT enabled the team of researchers to confirm the detection of HLX-1 in optical wavelengths and to measure a precise distance to it.

The lead author of the paper reporting this result, Dr Klaas Wiersema of Leicester’s Department of Physics and Astronomy, commented: “After our earlier discovery of the very bright X-ray source, we were very keen to find out just how far away it really is, so that we can work out how much radiation this black hole produces.

“We could see on images taken with big telescopes that a faint optical source was present at the location of the X-ray source, located near the core of a large and bright galaxy.

“We suspected that this faint optical source was directly associated with the X-ray source, but to be sure we had to study the light of this source in detail, using the Very Large Telescope in Chile.

“The data we got from the VLT were of a very high quality, and allowed us to separate the light of the big, bright galaxy from that of the faint optical source.

“Much to our delight we saw in the resulting measurements exactly what we were hoping for: the characteristic light of hydrogen atoms was detected allowing us to accurately measure the distance to this object. This provided conclusive proof that the black hole was indeed located inside the big, bright galaxy, and that HLX-1 is the brightest ultra-luminous X-ray source known.

“Now that we have established the distance to this black hole and now we know where it lives, we would like to find out what makes this source so bright, and how it ended up in this big galaxy.”

This is a very important result as it is consistent with the idea that HLX-1 contains an intermediate mass black hole. Ultra-luminous X-ray sources are among the most promising candidates for intermediate mass black holes, with masses between stellar mass black holes (around ~3-20 times the mass of the Sun) and the super-massive black holes found in the centres of most galaxies (around 1 million — 1 billion times the mass of the Sun).

The research team can now conclusively prove that HLX-1 is not in our own Galaxy, nor is it a super-massive black hole in the centre of a distant background galaxy. This result also confirms that it really is as bright as they thought it was.

Dr Didier Barret, of the Centre d’Etude Spatiale des Rayonnements in France, commented: “The XMM-Newton and Swift X-ray observatories are keeping a close eye on this source. The latest data, which was obtained while HLX-1 was very faint, indicates that it is behaving in a very similar way to stellar mass black holes in our own Galaxy, but at a level ~100 — 1,000 times brighter.”

Dr Sean Farrell, also in the Leicester Department of Physics and Astronomy, commented: “This is very difficult to explain without the presence of an intermediate mass black hole of between ~500 and 10,000 times the mass of the Sun. HLX-1 is therefore (so far!) weathering the scrutiny of the international astronomy community.”

The centres of most galaxies are thought to contain super-massive black holes, and these powerhouses have an enormous impact on the surrounding galaxy. Super-massive black holes deposit an immense amount of energy into their host galaxies, which has dramatic consequences for the formation of stars and the growth of the galaxy as a whole. Intermediate mass black holes may be the building blocks of super-massive black holes.

“Understanding how super-massive black holes form and grow is thus crucial to our comprehension of the formation and evolution of galaxies, which in turn goes part of the way to answering one of the really big questions: How did our own Galaxy form and evolve?

“We are very pleased with this result, as it confirms our original discovery of the record breaking ultra-luminous X-ray source. In order to ensure the success of this project, we carefully prepared the VLT observations using data from the US-operated Magellan Telescopes. The VLT data analysis was especially complicated on this project, as it is very difficult to disentangle the signature in optical wavelengths of HLX-1 from the bright galaxy in which it lies.

“This work relied heavily on the expertise of researchers at the University of Leicester, and is testament to the high level of skills that are concentrated in our department, which works on some of the biggest questions in astronomy today. This is fitting as we are currently celebrating the 50th anniversary of the founding of the astronomy group here at Leicester.”

Whether all ultra-luminous X-ray sources contain intermediate mass black holes is still quite uncertain. Dr Farrell’s research team will continue studying HLX-1 in order to understand how it formed, where it is located, and what is feeding it.

In order to do this they have been granted time on the Hubble Space Telescope to take the highest ever resolution images of this host galaxy, which will allow them to investigate in detail the nature of the environment around HLX-1 and the galaxy which hosts it. Once the Hubble observations are performed, most of the great observatories would have been used to study this source.

The next step will be to find out if there are more objects as extreme as this one, and to compare what they know about HLX-1 with the larger population of ultra-luminous X-ray sources. This will help them understand how many intermediate mass black holes might be out there, and where they are likely to find them.

The research team, their institutions and their funding bodies are: Sean Farrell, University of Leicester, Science and Technology Facilities Council (STFC) Klaas Wiersema, University of Leicester, STFC Natalie Webb, Centre d’Etude Spatiale des Rayonnements (CESR), Centre National de la Recherche Scientifique (CNRS) Mathieu Servillat, Harvard-Smithsonian Center for Astrophysics, NASA Thomas Maccarone, University of Southampton, STFC Didier Barret, CESR, CNRS Olivier Godet, CESR, CNRS.

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Leicester, via EurekAlert!, a service of AAAS.

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ScienceDaily (Aug. 19, 2010) — An international team of astronomers using gravitational lensing observations from the NASA/ESA Hubble Space Telescope has taken an important step forward in the quest to solve the riddle of dark energy, a phenomenon which mysteriously appears to power the Universe’s accelerating expansion.

Their results appear in the 20 August 2010 issue of the journal Science.

Normal matter like that found in stars, planets and dust clouds only makes up a tiny fraction of the mass-energy content of the Universe. It is dwarfed by the amount of dark matter — which is invisible, but can be detected by its gravitational pull. In turn, the amount of dark matter in the Universe is itself overwhelmed by the diffuse dark energy that permeates the entire Universe. Scientists believe that the pressure exerted by this dark energy is what pushes the Universe to expand at an ever-increasing rate.

Probing the nature of dark energy is, therefore, one of the key challenges in modern cosmology. Since its discovery in 1998, the quest has been to characterise and understand it better. This work presents an entirely new way to do so.

Eric Jullo, lead author of a new paper in the journal Science explains: “Dark energy is characterised by the relationship between its pressure and its density: this is known as its equation of state. Our goal was to try to quantify this relationship. It teaches us about the properties of dark energy and how it has affected the development of the Universe.”

The team measured the properties of the gravitational lensing in the galaxy cluster Abell 1689. Gravitational lensing is a phenomenon predicted by Einstein’s theory of general relativity, and was here used by the team to probe how the cosmological distances (and thus the shape of space-time) are modified by dark energy. At cosmic distances, a huge cluster of galaxies in the foreground has so much mass that its gravitational pull bends beams of light from very distant galaxies, producing distorted images of the faraway objects. The distortion induced by the lens depends in part on the distances to the objects, which have been precisely measured with large ground-based telescopes such as ESO’s Very Large Telescope and the Keck Telescopes.

“The precise effects of lensing depend on the mass of the lens, the structure of space-time, and the relative distance between us, the lens and the distant object behind it,” explains Priyamvada Natarajan, a co-author of the paper. “It’s like a magnifying glass, where the image you get depends on the shape of the lens and how far you hold it from the object you’re looking at. If you know the shape of the lens and the image you get, you can work out the path that light followed between the object and your eye.”

Looking at the distorted images allows astronomers to reconstruct the path that light from distant galaxies takes to make its long journey to Earth. It also lets them study the effect of dark energy on the geometry of space in the light path from the distant objects to the lensing cluster and then from the cluster to us. As dark energy pushes the Universe to expand ever faster, the precise path that the light beams follow as they travel through space and are bent by the lens is subtly altered. This means that the distorted images from the lens encapsulate information about the underlying cosmology, as well as about the lens itself.

So why is the geometry of the Universe such a big issue?

“The geometry, the content and the fate of the Universe are all intricately linked,” says Natarajan. “If you know two, you can deduce the third. We already have a pretty good knowledge of the Universe’s mass-energy content, so if we can get a handle on its geometry then we will be able to work out exactly what the fate of the Universe will be.”

The real strength of this new result is that it devises a totally new way to extract information about the elusive dark energy. It is a unique and powerful one, and offers great promise for future applications.

According to the scientists, their method required multiple, meticulous steps to develop. They spent several years developing specialised mathematical models and precise maps of the matter — both dark and “normal” — that together constitute the Abell 1689 cluster.

Co-author Jean-Paul Kneib explains: “Using our unique method in conjunction with others, we were able to come up with results that were far more precise than any achieved before.”

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The international team of astronomers in this study consists of Eric Jullo (Jet Propulsion Laboratory/ Cal Tech, USA and Laboratoire d’Astrophysique de Marseille, France), Priyamvada Natarajan (Yale University, USA), Jean-Paul Kneib (Laboratoire d’Astrophysique de Marseille, France), Anson D’Aloisio (Yale University, USA), Marceau Limousin (Laboratoire d’Astrophysique de Marseille, France and University of Copenhagen, Denmark), Johan Richard (Durham University, UK) and Carlo Schimd (Laboratoire d’Astrophysique de Marseille, France)

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by ESA/Hubble Information Centre.

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Journal Reference:

1. Eric Jullo, Priyamvada Natarajan, Jean-Paul Kneib, Anson D%u2019Aloisio, Marceau Limousin, Johan Richard, and Carlo Schimd. Cosmological Constraints from Strong Gravitational Lensing in Clusters of Galaxies. Science, 2010; 329 (5994): 924-927 DOI: 10.1126/science.1185759

(Sep. 8, 2010) — Two asteroids, several meters in diameter and in unrelated orbits, will pass within the moon’s distance of Earth on Wednesday, Sept. 8.

Both asteroids should be observable near closest approach to Earth with moderate-sized amateur telescopes. Neither of these objects has a chance of hitting Earth. A 10-meter-sized near-Earth asteroid from the undiscovered population of about 50 million would be expected to pass almost daily within a lunar distance, and one might strike Earth’s atmosphere about every 10 years on average.

The Catalina Sky Survey near Tucson, Ariz., discovered both objects on the morning of Sunday, Sept. 5, during a routine monitoring of the skies. The Minor Planet Center in Cambridge, Mass., first received the observations Sunday morning, determined preliminary orbits and concluded that both objects would pass within the distance of the moon about three days after their discovery.

Near-Earth asteroid 2010 RX30 is estimated to be 32 to 65 feet (10 to 20 meters) in size and will pass within 0.6 lunar distances of Earth (about 154,000 miles, or 248,000 kilometers) at 2:51 a.m. PDT (5:51 a.m. EDT) Wednesday. The second object, 2010 RF12, estimated to be 20 to 46 feet (6 to 14 meters) in size, will pass within 0.2 lunar distances (about 49,088 miles or 79,000 kilometers) a few hours later at 2:12 p.m. PDT (5:12 pm EDT).

More information about asteroids is available at http://www.jpl.nasa.gov/asteroidwatch/ . You can also follow the latest news about asteroids on Twitter at @asteroidwatch .

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by NASA/Jet Propulsion Laboratory.

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ScienceDaily (Aug. 19, 2010) — The Alpha Magnetic Spectrometer (AMS), an experiment that will search for antimatter and dark matter in space, leaves CERN August 24 on the next leg of its journey to the International Space Station. The AMS detector is being transported from CERN to Geneva International Airport in preparation for its planned departure from Switzerland on 26 August, when it will be flown to the Kennedy Space Center in Florida on board a US Air Force Galaxy transport aircraft.

AMS will examine fundamental issues about matter and the origin and structure of the Universe directly from space. Its main scientific target is the search for dark matter and antimatter, in a programme that is complementary to that of the Large Hadron Collider.

Last February the AMS detector travelled from CERN to the European Space Research and Technology Centre (ESTEC) in Noordwijk (Netherlands) for testing to certify its readiness for travel into space. Following the completion of the testing, the AMS collaboration decided to return the detector to CERN for final modifications. In particular, the detector’s superconducting magnet was replaced by the permanent magnet from the AMS-01 prototype, which had already flown into space in 1998. The reason for the decision was that the operational lifetime of the superconducting magnet would have been limited to three years, because there is no way of refilling the magnet with liquid helium, necessary to maintain the magnet’s superconductivity, on board the space station. The permanent magnet, on the other hand, will now allow the experiment to remain operational for the entire lifetime of the ISS.

Following its return to CERN, the AMS detector was therefore reconfigured with the permanent magnet before being tested with CERN particle beams. The tests were used to validate and calibrate the new configuration before the detector leaves Europe for the last time.

Upon arrival at the Kennedy Space Center, AMS will be installed in a clean room for a few more tests. A few weeks later, the detector will be moved to the space shuttle. NASA is planning the last flight of the space shuttle programme, which will carry AMS into space, for the end of February 2011.

Once docked to the ISS, AMS will search for antimatter and dark matter by measuring cosmic rays. Data collected in space by AMS will be transmitted to Houston (USA) and on to CERN’s Prévessin site, where the detector control centre will be located, and to a number of regional physics analysis centres set up by the collaborating institutes.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by CERN.

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(Sep. 8, 2010) — The European Southern Observatory has released a spectacular new image of NGC 300, a spiral galaxy similar to the Milky Way, and located in the nearby Sculptor Group of galaxies. Taken with the Wide Field Imager (WFI) at ESO’s La Silla Observatory in Chile, this 50-hour exposure reveals the structure of the galaxy in exquisite detail. NGC 300 lies about six million light-years away and appears to be about two thirds the size of the full Moon on the sky.

Originally discovered from Australia by the Scottish astronomer James Dunlop early in the nineteenth century, NGC 300 is one of the closest and most prominent spiral galaxies in the southern skies and is bright enough to be seen easily in binoculars. It lies in the inconspicuous constellation of Sculptor, which has few bright stars, but is home to a collection of nearby galaxies that form the Sculptor Group. Other members that have been imaged by ESO telescopes include NGC 55, NGC 253 and NGC 7793. Many galaxies have at least some slight peculiarity, but NGC 300 seems to be remarkably normal. This makes it an ideal specimen for astronomers studying the structure and content of spiral galaxies such as our own.

This picture from the Wide Field Imager (WFI) at ESO’s La Silla Observatory in Chile was assembled from many individual images taken through a large set of different filters with a total exposure time close to 50 hours. The data was acquired over many observing nights, spanning several years. The main purpose of this extensive observational campaign was to take an unusually thorough census of the stars in the galaxy, counting both the number and varieties of the stars, and marking regions, or even individual stars, that warrant deeper and more focussed investigation. But such a rich data collection will also have many other uses for years to come. By observing the galaxy with filters that isolate the light coming specifically from hydrogen and oxygen, the many star-forming regions along NGC 300′s spiral arms are shown with particular clarity in this image as red and pink clouds. With its huge field of view, 34 x 34 arcminutes, similar to the apparent size of the full Moon in the sky, the WFI is an ideal tool for astronomers to study large objects such as NGC 300.

NGC 300 is also the home of many interesting astronomical phenomena that have been studied with ESO telescopes. ESO astronomers recently discovered the most distant and one of the most massive stellar-mass black holes yet found in this galaxy, as the partner of a hot and luminous Wolf-Rayet star in a binary system. NGC 300 and another galaxy, NGC 55, are slowly spinning around and towards each other, in the early stages of a lengthy merging process. The current best estimate of the distance to the NCG 300 was also determined by astronomers using ESO’s Very Large Telescope at the Paranal Observatory, among others.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by European Southern Observatory – ESO.

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ScienceDaily (Aug. 17, 2010) — A large collaboration of physicists working at the Fermilab Tevatron particle collider has discovered evidence of an explanation for the prevalence of matter over antimatter in the universe. They found that colliding protons in their experiment produced short-lived B meson particles that almost immediately broke down into debris that included slightly more matter than antimatter. The two types of matter annihilate each other, so most of the material coming from these sorts of decays would disappear, leaving an excess of regular matter behind. This sort of matter/antimatter asymmetry accounts for the fact that just about all the material in the universe is made of the normal matter we’re familiar with.

The results are being published this week in papers appearing simultaneously in the APS journals Physical Review Letters and Physical Review D.

Physicists have long known about processes described by current physics theory that would produce tiny excesses of matter, but the amounts the theories predict are far smaller than necessary to create the universe we observe. The Tevatron experiments suggest that we are on the verge of accounting for the quantities of matter that exist today. But the truly exciting implication is that the experiment implies that there is new physics, beyond the widely accepted Standard Model, that must be at work. If that’s the case, major scientific developments lie ahead.

The results emerge from a complicated and challenging analysis, and have yet to be confirmed by other experiments. If the matter/antimatter imbalance holds up under the scrutiny of researchers at the Large Hadron Collider in Europe and competing research groups at Fermilab, it will likely stand as one of the most significant milestones in high-energy physics, according to Roy Briere of Carnegie Mellon University in Pittsburgh. Briere summarizes the experimental results and their implications in a Viewpoint article in the current edition of APS Physics.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Physical Society, via EurekAlert!, a service of AAAS.

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(Sep. 7, 2010) — Volcanoes display the awesome power of Nature like few other events. Earlier this year, ash from an Icelandic volcano disrupted air travel throughout much of northern Europe. Yet this recent eruption pales next to the fury of Jupiter’s moon Io, the most volcanic body in our solar system.

Now that astronomers are finding rocky worlds orbiting distant stars, they’re asking the next logical questions: Do any of those worlds have volcanoes? And if so, could we detect them? Work by theorists at the Harvard-Smithsonian Center for Astrophysics suggests that the answer to the latter is a qualified “Yes.”

“You would need something truly earthshaking, an eruption that dumped a lot of gases into the atmosphere,” said Smithsonian astronomer Lisa Kaltenegger. “Using the James Webb Space Telescope, we could spot an eruption 10 to 100 times the size of Pinatubo for the closest stars,” she added.

Astronomers are decades away from being able to image the surface of an alien world, or exoplanet. However, in a few cases they have been able to detect exoplanet atmospheres for gas giants known as “hot Jupiters.” An eruption sends out fumes and various gases, so volcanic activity on a rocky exoplanet might leave a telltale atmospheric signature.

To examine which volcanic gases might be detectable, Kaltenegger and her Harvard colleagues, Wade Henning and Dimitar Sasselov, developed a model for eruptions on an Earth-like exoplanet based on the present-day Earth. They found that sulfur dioxide from a very large, explosive eruption is potentially measurable because a lot is produced and it is slow to wash out of the air.

“Our first sniffs of volcanoes from an alien Earth might be pretty rank!” Kaltenegger said. “Seeing a volcanic eruption on an exoplanet will show us similarities or differences among rocky worlds.”

The 1991 eruption of Mount Pinatubo in the Philippines spewed about 17 million tons of sulfur dioxide into the stratosphere — a layer of air 6 to 30 miles above Earth’s surface. The largest volcanic eruption in recorded history, the 1815 Tambora event, was about 10 times more powerful.

Such gigantic eruptions are infrequent, so astronomers would have to monitor many Earth-sized planets for years to catch one in the act. However, if alien worlds are more volcanically active than Earth, success might be more likely.

“A Tambora-sized eruption doesn’t happen often here, but could be more common on a younger planet, or a strongly tidally active planet — analogous to Io,” said Henning. “Once you detected one eruption, you could keep watch for further ones, to learn if frequent eruptions are common on other planets.”

To look for volcanic sulfur dioxide, astronomers would rely on a technique known as the secondary eclipse, which requires the exoplanet to cross behind its star as seen from Earth. By collecting light from the star and planet, then subtracting the light from the star (while the planet is hidden), astronomers are left with the signal from the planet alone. They can search that signal for signs of particular chemical molecules.

Due to its proximity, a hypothetical Earth or super-Earth orbiting Alpha Centauri would offer a best-case scenario for a sun-like star. A super-Earth orbiting a smaller host star close to our own Sun would show the biggest signal. But any Earth-like planet less than 30 light-years away could show faint signs of volcanism when studied with the James Webb Space Telescope.

This research will be published in The Astrophysical Journal.

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Harvard-Smithsonian Center for Astrophysics.

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