Jan 10 2012

From The Space Library

RELEASE: 12-007 HUBBLE PINPOINTS FARTHEST PROTOCLUSTER OF GALAXIES EVER SEEN

WASHINGTON -- Using NASA's Hubble Space Telescope, astronomers have uncovered a cluster of galaxies in the initial stages of development. It is the most distant such grouping ever observed in the early universe. In a random sky survey made in near-infrared light, Hubble found five tiny galaxies clustered together 13.1 billion light-years away. They are among the brightest galaxies at that epoch and very young -- existing just 600 million years after the big bang. Galaxy clusters are the largest structures in the universe, comprising hundreds to thousands of galaxies bound together by gravity. The developing cluster, or protocluster, is seen as it looked 13 billion years ago. Presumably, it has grown into one of today's massive galactic cities, comparable to the nearby Virgo cluster of more than 2,000 galaxies. "These galaxies formed during the earliest stages of galaxy assembly, when galaxies had just started to cluster together," said Michele Trenti of the University of Colorado at Boulder and the Institute of Astronomy at the University of Cambridge in the United Kingdom. "The result confirms our theoretical understanding of the buildup of galaxy clusters. And, Hubble is just powerful enough to find the first examples of them at this distance." Trenti presented the results today at the American Astronomical Society meeting in Austin, Texas. The study will be published in an upcoming issue of The Astrophysical Journal. Most galaxies in the universe reside in groups and clusters, and astronomers have probed many mature galactic cities in detail as far as 11 billion light-years away. Finding clusters in the early phases of construction has been challenging because they are rare, dim and widely scattered across the sky. "We need to look in many different areas because the odds of finding something this rare are very small," said Trenti, who used Hubble's sharp-eyed Wide Field Camera 3 (WFC3) to pinpoint the cluster galaxies. "The search is hit and miss. Typically, a region has nothing, but if we hit the right spot, we can find multiple galaxies." Hubble's observations demonstrate the progressive buildup of galaxies. They also provide further support for the hierarchical model of galaxy assembly, in which small objects accrete mass, or merge, to form bigger objects over a smooth and steady but dramatic process of collision and collection. Because the distant, fledgling clusters are so dim, the team hunted for the systems' brightest galaxies. These galaxies act as billboards, advertising cluster construction zones. From computer simulations, the astronomers expect galaxies at early epochs to be clustered together. Because brightness correlates with mass, the most luminous galaxies pinpoint the location of developing clusters. These powerful light beacons live in deep wells of dark matter, an invisible form of matter that makes up the underlying gravitational scaffolding for construction. The team expects many fainter galaxies that were not seen in these observations to inhabit the same neighborhood. The five bright galaxies spotted by Hubble are about one-half to one-tenth the size of our Milky Way, yet are comparable in brightness. The galaxies are bright and massive because they are being fed large amounts of gas through mergers with other galaxies. The team's simulations show that the galaxies eventually will merge and form the brightest central galaxy in the cluster, a giant elliptical similar to the Virgo Cluster's M87. The observations are part of the Brightest Reionizing Galaxies survey, which uses Hubble's WFC3 to search for the brightest galaxies around 13 billion years ago, when light from the first stars burned off a fog of cold hydrogen in a process called reionization. The team estimated the distance to the newly found galaxies based on their colors, but the astronomers plan to follow up with spectroscopic observations, which measure the expansion of space. Those observations will help astronomers precisely calculate the cluster's distance and yield the velocities of the galaxies, which will show whether they are gravitationally bound to each other. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

RELEASE: 12-008 NASA'S CHANDRA FINDS LARGEST GALAXY CLUSTER IN EARLY UNIVERSE

Washington -- An exceptional galaxy cluster, the largest seen in the distant universe, has been found using NASA's Chandra X-ray Observatory and the National Science Foundation-funded Atacama Cosmology Telescope (ACT) in Chile. Officially known as ACT-CL J0102-4915, the galaxy cluster has been nicknamed "El Gordo" ("the big one" or "the fat one" in Spanish) by the researchers who discovered it. The name, in a nod to the Chilean connection, describes just one of the remarkable qualities of the cluster, which is located more than 7 billion light years from Earth. This large distance means it is being observed at a young age. "This cluster is the most massive, the hottest, and gives off the most X-rays of any known cluster at this distance or beyond," said Felipe Menanteau of Rutgers University in New Brunswick, N.J., who led the study. Galaxy clusters, the largest objects in the universe that are held together by gravity, form through the merger of smaller groups or sub-clusters of galaxies. Because the formation process depends on the amount of dark matter and dark energy in the universe, clusters can be used to study these mysterious phenomena. Dark matter is material that can be inferred to exist through its gravitational effects, but does not emit and absorb detectable amounts of light. Dark energy is a hypothetical form of energy that permeates all space and exerts a negative pressure that causes the universe to expand at an ever-increasing rate. "Gigantic galaxy clusters like this are just what we were aiming to find," said team member Jack Hughes, also of Rutgers. "We want to see if we can understand how these extreme objects form using the best models of cosmology that are currently available." Although a cluster of El Gordo's size and distance is extremely rare, it is likely that its formation can be understood in terms of the standard Big Bang model of cosmology. In this model, the universe is composed predominantly of dark matter and dark energy, and began with a Big Bang about 13.7 billion years ago. The team of scientists found El Gordo using ACT thanks to the Sunyaev-Zeldovich effect. In this phenomenon, photons in the cosmic microwave background interact with electrons in the hot gas that pervades these enormous galaxy clusters. The photons acquire energy from this interaction, which distorts the signal from the microwave background in the direction of the clusters. The magnitude of this distortion depends on the density and temperature of the hot electrons and the physical size of the cluster. X-ray data from Chandra and the European Southern Observatory's Very Large Telescope, an 8-meter optical observatory in Chile, show El Gordo is, in fact, the site of two galaxy clusters colliding at several million miles per hour. This and other characteristics make El Gordo akin to the well-known object called the Bullet Cluster, which is located almost 4 billion light years closer to Earth. As with the Bullet Cluster, there is evidence that normal matter, mainly composed of hot, X-ray bright gas, has been wrenched apart from the dark matter in El Gordo. The hot gas in each cluster was slowed down by the collision, but the dark matter was not. "This is the first time we've found a system like the Bullet Cluster at such a large distance," said Cristobal Sifon of Pontificia Universidad de Catolica de Chile (PUC) in Santiago. "It's like the expression says: if you want to understand where you're going, you have to know where you've been." These results on El Gordo are being announced at the 219th meeting of the American Astronomical Society in Austin, Texas. A paper describing these results has been accepted for publication in The Astrophysical Journal. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass

RELEASE: 12-009 NASA'S RXTE HELPS PINPOINT LAUNCH OF 'BULLETS' IN A BLACK HOLE'S JET

WASHINGTON -- Using observations from NASA's Rossi X-ray Timing Explorer (RXTE) satellite and the National Science Foundation's (NSF) Very Long Baseline Array (VLBA) radio telescope, an international team of astronomers has identified the moment when a black hole in our galaxy launched superfast knots of gas into space. Racing outward at about one-quarter the speed of light, these "bullets" of ionized gas are thought to arise from a region located just outside the black hole's event horizon, the point beyond which nothing can escape. "Like a referee at a sports game, we essentially rewound the footage on the bullets' progress, pinpointing when they were launched," said Gregory Sivakoff of the University of Alberta in Canada. He presented the findings today at the American Astronomical Society meeting in Austin, Texas. "With the unique capabilities of RXTE and the VLBA, we can associate their ejection with changes that likely signaled the start of the process." The research centered on the mid-2009 outburst of a binary system known as H1743--322, located about 28,000 light-years away toward the constellation Scorpius. Discovered by NASA's HEAO-1 satellite in 1977, the system is composed of a normal star and a black hole of modest but unknown masses. Their orbit around each other is measured in days, which puts them so close together that the black hole pulls a continuous stream of matter from its stellar companion. The flowing gas forms a flattened accretion disk millions of miles across, several times wider than our sun, centered on the black hole. As matter swirls inward, it is compressed and heated to tens of millions of degrees, so hot that it emits X-rays. Some of the infalling matter becomes re-directed out of the accretion disk as dual, oppositely directed jets. Most of the time, the jets consist of a steady flow of particles. Occasionally, though, they morph into more powerful outflows that hurl massive gas blobs at significant fractions of the speed of light. In early June 2009, H1743--322 underwent this transition as astronomers watched with RXTE, the VLBA, the Very Large Array near Socorro, N.M., and the Australia Telescope Compact Array (ATCA) near Narrabri in New South Wales. The observatories captured changes in the system's X-ray and radio emissions as the transformation occurred. From May 28 to June 2, the system's X-ray and radio emissions were fairly steady, although RXTE data show that cyclic X-ray variations, known as quasi-periodic oscillations or QPOs, gradually increased in frequency over the same period. On June 4, ATCA measurements showed that the radio emission had faded significantly. Astronomers interpret QPOs as signals produced by the interaction of clumps of ionized gas in the accretion disk near the black hole. When RXTE next looked at the system on June 5, the QPOs were gone. The same day, the radio emission increased. An extremely detailed VLBA image revealed a bright, radio-emitting bullet of gas moving outward from the system in the direction of one of the jets. On June 6, a second blob, moving away in the opposite direction, was seen. Until now, astronomers had associated the onset of the radio outburst with the bullet ejection event. However, based on the VLBA data, the team calculated that the bullets were launched on June 3, about two days before the main radio flare. A paper on the findings will be published in the Monthly Notices of the Royal Astronomical Society. "This research provides new clues about the conditions needed to initiate a jet and can guide our thinking about how it happens," said Chris Done, an astrophysicist at the University of Durham, England, who was not involved in the study. A super-sized version of the same phenomenon occurs at the center of an active galaxy, where a black hole weighing millions to billions of times our sun's mass can drive outflows extending millions of light-years. "Black hole jets in binary star systems act as fast-forwarded versions of their galactic-scale cousins, giving us insights into how they work and how their enormous energy output can influence the growth of galaxies and clusters of galaxies," said lead researcher James Miller-Jones at the International Center for Radio Astronomy Research at Curtin University in Perth, Australia. The Rossi X-ray Timing Explorer, which operated from Dec. 1995 to Jan. 2012, was managed by NASA's Goddard Space Flight Center in Greenbelt, Md. The VLBA, the world's largest and highest-resolution astronomical instrument, is controlled from the National Radio Astronomy Observatory's Domenici Science Operations Center.

RELEASE: 12-010 NASA'S FERMI SPACE TELESCOPE EXPLORES NEW ENERGY EXTREMES

WASHINGTON -- After more than three years in space, NASA's Fermi Gamma-ray Space Telescope is extending its view of the high-energy sky into a largely unexplored electromagnetic range. Today, the Fermi team announced its first census of energy sources in this new realm. Fermi's Large Area Telescope (LAT) scans the entire sky every three hours, continually deepening its portrait of the sky in gamma rays, the most energetic form of light. While the energy of visible light falls between about 2 and 3 electron volts, the LAT detects gamma rays with energies ranging from 20 million to more than 300 billion electron volts (GeV). At higher energies, gamma rays are rare. Above 10 GeV, even Fermi's LAT detects only one gamma ray every four months. "Before Fermi, we knew of only four discrete sources above 10 GeV, all of them pulsars," said David Thompson, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md. "With the LAT, we've found hundreds, and we're showing for the first time just how diverse the sky is at these high energies." Any object producing gamma rays at these energies is undergoing extraordinary astrophysical processes. More than half of the 496 sources in the new census are active galaxies, where matter falling into a supermassive black hole powers jets that spray out particles at nearly the speed of light. Only about 10 percent of the known sources lie within our own galaxy. They include rapidly rotating neutron stars called pulsars, the expanding debris from supernova explosions, and in a few cases, binary systems containing massive stars. More than a third of the sources are completely unknown, having no identified counterpart detected in other parts of the spectrum. With the new catalog, astronomers will be able to compare the behavior of different sources across a wider span of gamma-ray energies for the first time. Just as bright infrared sources may fade to invisibility in the ultraviolet, some of the gamma-ray sources above 1 GeV vanish completely when viewed at higher, or "harder," energies. One example is the well-known radio galaxy NGC 1275, which is a bright, isolated source below 10 GeV. At higher energies it fades appreciably and another nearby source begins to appear. Above 100 GeV, NGC 1275 becomes undetectable by Fermi, while the new source, the radio galaxy IC 310, shines brightly. The Fermi hard-source list is the product of an international team led by Pascal Fortin at the Ecole Polytechnique's Laboratoire Leprince-Ringuet in Palaiseau, France, and David Paneque at the Max Planck Institute for Physics in Munich. The catalog serves as an important roadmap for ground-based facilities called Atmospheric Cherenkov Telescopes, which have amassed about 130 gamma-ray sources with energies above 100 GeV. They include the Major Atmospheric Gamma Imaging Cherenkov telescope (MAGIC) on La Palma in the Canary Islands, the Very Energetic Radiation Imaging Telescope Array System (VERITAS) in Arizona, and the High Energy Stereoscopic System (H.E.S.S.) in Namibia. "Our catalog will have a significant impact on ground-based facilities' work by pointing them to the most likely places to find gamma-ray sources emitting above 100 GeV," Paneque said. Compared to Fermi's LAT, these ground-based observatories have much smaller fields of view. They also make fewer observations because they cannot operate during daytime, bad weather or a full moon. "As Fermi's exposure constantly improves our view of hard sources, ground-based telescopes are becoming more sensitive to lower-energy gamma rays, allowing us to bridge these two energy regimes," Fortin added. NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership. Fermi is managed by Goddard. It was developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

RELEASE: 12-014 NASA'S ONLINE RADIO STATION ROCKS SMARTPHONES

MOFFETT FIELD, Calif. -- NASA's Third Rock Radio just got mobile. Updates to the NASA App for iPhone, iPod Touch, iPad and Android now include a feature to listen to the agency's new online alternative rock radio station. "Now you can listen to great music in the same app that still provides all of NASA's amazing content wherever you are," said Jerry Colen, NASA App project manager at NASA's Ames Research Center in Moffett Field, Calif. Third Rock - America's Space Station launched with a new rock/indie/alternative format on Dec. 12, 2011. The station is being developed and operated at no cost to the government through a Space Act Agreement. The NASA Apps showcase a wealth of NASA content, including images, videos on-demand, live streaming video from NASA Television, mission information, feature stories and breaking news. Users also can find sighting opportunities for the International Space Station and track the positions of spacecraft orbiting Earth. App users easily can share NASA content on Facebook, Twitter or via e-mail.

CONTRACT RELEASE: C12-001 NASA AWARDS LAUNCH SERVICES PROGRAM SUPPORT CONTRACT

CAPE CANAVERAL, Fla. -- NASA has selected a.i. solutions Inc. of Lanham, Md., to receive a contract award that will enable the agency's Launch Services Program (LSP) to provide integrated services for the preparation and launch of NASA's next generation of scientific and exploration spacecraft. The Expendable Launch Vehicle Integrated Support 2 (ELVIS 2) contract has a potential maximum value of $138.1 million. This new contract resulted from a competitive, small business set-aside. The contract has a two-month phase-in period that begins February 2012, followed by a one-and-a-half-year base period extending from April 1, 2012, through Sept. 30, 2013. Two option periods are available that would bring the total period of performance to five years. The ELVIS 2 contract supports LSP and LSP-sponsored missions, activities and strategic initiatives for multiple NASA programs, the Defense Department and other government agencies and commercial launch activities. The contract will provide LSP with program management support; vehicle engineering and analysis; launch site support engineering; communications and telemetry; technical integration services; LSP programmatic safety, reliability and quality support; support at Vandenberg Air Force Base in California; information technology support; and special studies.