The Monster Of Monsters From The Dawn Of Time

This is an artist's impression of a quasar with a supermassive black hole in the distant universe.m Credit: Zhaoyu Li/NASA/JPL-Caltech/Misti Mountain Observatory

Scientists have discovered the brightest quasar in the early universe, powered by the most massive black hole yet known at that time. The international team led by astronomers from Peking University in China and from the University of Arizona announce their findings in the scientific journal Nature on Feb. 26. The discovery of this quasar, named SDSS J0100+2802, marks an important step in understanding how quasars, the most powerful objects in the universe, have evolved from the earliest epoch, only 900 million years after the Big Bang, which is thought to have happened 13.7 billion years ago. The quasar, with its central black hole mass of 12 billion solar masses and the luminosity of 420 trillion suns, is at a distance of 12.8 billion light-years from Earth. The discovery of this ultraluminous quasar also presents a major puzzle to the theory of black hole growth at early universe, according to Xiaohui Fan, Regents' Professor of Astronomy at the UA's Steward Observatory, who co-authored the study. "How can a quasar so luminous, and a black hole so massive, form so early in the history of the universe, at an era soon after the earliest stars and galaxies have just emerged?" Fan said. "And what is the relationship between this monster black hole and its surrounding environment, including its host galaxy? "This ultraluminous quasar with its supermassive black hole provides a unique laboratory to the study of the mass assembly and galaxy formation around the most massive black holes in the early universe." The quasar dates from a time close to the end of an important cosmic event that astronomers referred to as the "epoch of reionization": the cosmic dawn when light from the earliest generations of galaxies and quasars is thought to have ended the "cosmic dark ages" and transformed the universe into how we see it today. Discovered in 1963, quasars are the most powerful objects beyond our Milky Way galaxy, beaming vast amounts of energy across space as the supermassive black hole in their center sucks in matter from its surroundings. Thanks to the new generation of digital sky surveys, astronomers have discovered more than 200,000 quasars, with ages ranging from 0.7 billion years after the Big Bang to today. The newly discovered quasar SDSS J0100+2802 is the one with the most massive black hole and the highest luminosity among all known distant quasars. The background photo, provided by Yunnan Observatory, shows the dome of the

Credit: Zhaoyu Li/Shanghai Observatory

2.4meter telescope and the sky above it. Shining with the equivalent of 420 trillion suns, the new quasar is seven times brighter than the most distant quasar known (which is 13 billion years away). It harbors a black hole with mass of 12 billion solar masses, proving it to be the most luminous quasar with the most massive black hole among all the known high redshift (very distant) quasars. "By comparison, our own Milky Way galaxy has a black hole with a mass of only 4 million solar masses at its center; the black hole that powers this new quasar is 3,000 time heavier," Fan said. Feige Wang, a doctoral student from Peking University who is supervised jointly by Fan and Prof. Xue-Bing Wu at Peking University, the study's lead author, initially spotted this quasar for further study. "This quasar was first discovered by our 2.4-meter Lijiang Telescope in Yunnan, China, making it the only quasar ever discovered by a 2-meter telescope at such distance, and we're very proud of it," Wang said. "The ultraluminous nature of this quasar will allow us to make unprecedented measurements of the temperature, ionization state and metal content of the intergalactic medium at the epoch of reionization." Following the initial discovery, two telescopes in southern Arizona did the heavy lifting in determining the distance and mass of the black hole: the 8.4-meter Large Binocular Telescope, or LBT, on Mount Graham and the 6.5-meter Multiple Mirror Telescope, or MMT, on Mount Hopkins. Additional observations with the 6.5-meter Magellan Telescope in Las Campanas Observatory, Chile, and the 8.2-meter Gemini North Telescope in Mauna Kea, Hawaii, confirmed the results. "This quasar is very unique," said Xue-Bing Wu, a professor of the Department of Astronomy, School of Physics at Peking University and the associate director of the Kavli Institute of Astronomy and Astrophysics. "Just like the brightest lighthouse in the distant universe, its glowing light will help us to probe more about the early universe." Wu leads a team that has developed a method to effectively select quasars in the distant universe based on optical and near-infrared photometric data, in particular using data from the Sloan Digital Sky Survey and NASA's Wide-Field Infrared Explorer, or WISE, satellite. "This is a great accomplishment for the LBT," said Fan, who chairs the LBT Scientific Advisory Committee and also discovered the previous record holders for the most massive black hole in the early universe, about a fourth of the size of the newly discovered object. "The especially sensitive optical and infrared spectrographs of the LBT provided the early assessment of both the distance of the quasars and the mass of the black hole at the quasar's center." For Christian Veillet, director of the Large Binocular Telescope Observatory, or LBTO, this discovery demonstrates both the power of international collaborations and the benefit of using a variety of facilities spread throughout the world. "This result is particularly gratifying for LBTO, which is well on its way to full nighttime operations," Veillet said. "While in this case the authors used two different instruments in series, one for visible light spectroscopy and one for near-infrared imaging, LBTO will soon offer a pair of instruments that can be used simultaneously, effectively doubling the number of observations possible in clear skies and ultimately creating even more exciting science." To further unveil the nature of this remarkable quasar, and to shed light on the physical processes that led to the formation of the earliest supermassive black holes, the research team will carry out further investigations on this quasar with more international telescopes, including the Hubble Space Telescope and the Chandra X-ray Telescope. Contacts and sources: Daniel Stolte, University of Arizona, Source: Article

Read More........→July 04, 2015

Extreme Power of Black Hole Revealed

Astronomers have used NASA's Chandra X-ray Observatory and a suite of other telescopes to reveal one of the most powerful black holes known. The black hole has created enormous structures in the hot gas surrounding it and prevented trillions of stars from forming
The black hole is in a galaxy cluster named RX J1532.9+3021 (RX J1532 for short), located about 3.9 billion light years from Earth. The image here is a composite of X-ray data from Chandra revealing hot gas in the cluster in purple and optical data from the Hubble Space Telescope showing galaxies in yellow. The cluster is very bright in X-rays implying that it is extremely massive, with a mass about a quadrillion - a thousand trillion - times that of the sun. At the center of the cluster is a large elliptical galaxy containing the supermassive black hole. The large amount of hot gas near the center of the cluster presents a puzzle. Hot gas glowing with X-rays should cool, and the dense gas in the center of the cluster should cool the fastest. The pressure in this cool central gas is then expected to drop, causing gas further out to sink in towards the galaxy, forming trillions of stars along the way. However, astronomers have found no such evidence for this burst of stars forming at the center of this cluster. This problem has been noted in many galaxy clusters but RX J1532 is an extreme case, where the cooling of gas should be especially dramatic because of the high density of gas near

Artist's view of the Chandra X-ray Observatory

the center. Out of the thousands of clusters known to date, less than a dozen are as  extreme as RX J1532. The Phoenix Cluster is the most extreme, where, conversely, large numbers of stars have been observed to be forming. What is stopping large numbers of stars from forming in RX J1532? Images from the Chandra X-ray Observatory and the NSF's Karl G. Jansky Very Large Array (VLA) have provided an answer to this question. The X-ray image shows two large cavities in the hot gas on either side of the central galaxy. The Chandra image has been specially processed to emphasize the cavities. Both cavities are aligned with jets seen in radio images from the VLA. The location of the supermassive black hole between the cavities is strong evidence that the supersonic jets generated by the black hole have drilled into the hot gas and pushed it aside, forming the cavities. Shock fronts - akin to sonic booms - caused by the expanding cavities and the release of energy by sound waves reverberating through the hot gas provide a source of heat that prevents most of the gas from cooling and forming new stars. The cavities are each about 100,000 light years across, roughly equal to the width of the Milky Way galaxy. The power needed to generate them is among the largest known in galaxy clusters. For example, the power is almost 10 times greater than required to create the well-known cavities in Perseus. Although the energy to power the jets must have been generated by matter falling toward the black hole, no X-ray emission has been detected from infalling material. This result can be explained if the black hole is "ultramassive" rather than supermassive, with a mass more than 10 billion times that of the sun. Such a black hole should be able to produce powerful jets without consuming large amounts of mass, resulting in very little radiation from material falling inwards. Another possible explanation is that the black hole has a mass only about a billion times that of the sun but is spinning extremely rapidly. Such a black hole can produce more powerful jets than a slowly spinning black hole when consuming the same amount of matter. In both explanations the black hole is extremely massive. A more distant cavity is also seen at a different angle with respect to the jets, along a north-south direction. This cavity is likely to have been produced by a jet from a much older outburst from the black hole. This raises the question of why this cavity is no longer aligned with the jets. There are two possible explanations. Either large-scale motion of the gas in the cluster has pushed it to the side or the black hole is precessing, that is, wobbling like a spinning top. A paper describing this work was published in the November 10th, 2013 issue of The Astrophysical Journal and is available online (http://arxiv.org/abs/1306.0907). The first author is Julie Hlavacek-Larrondo from Stanford University. The Hubble data used in this analysis were from the Cluster Lensing and Supernova survey, led by Marc Postman from Space Telescope Science Institute: http://www.stsci.edu/~postman/CLASH/Home.html, 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 in Cambridge, Mass., controls Chandra's science and flight operations. For more information about Chandra X-ray Observatory, visit: http://www.nasa.gov/mission_pages/chandra/main/, Chandra on Flickr: http://www.flickr.com/photos/nasamarshall/sets/72157606205297786/, Images, Text, Credits: X-ray: NASA/CXC/Stanford/J.Hlavacek-Larrondo et al, Optical: NASA/ESA/STScI/M.Postman & CLASH team.Greetings, Orbiter.ch, Source: Orbiter.ch Space News

Read More........→March 19, 2014

Birth Of Black Hole Kills The Radio Star

Astronomers led by a Curtin University researcher have discovered a new population of exploding stars that “switch off” their radio transmissions before collapsing into a Black Hole. These exploding stars use all of their energy to emit one last strong beam of highly energetic radiation – known as a gamma-ray burst – before they die. Up until now, it was thought all gamma-ray bursts were followed by a radio afterglow – a premise that a team of Australian astronomers of the Centre for All-sky Astrophysics (CAASTRO) at Curtin University and theUniversity of Sydney originally set out to prove correct. “But we were wrong. After studying an ultra-sensitive image of gamma-ray bursts with no afterglow, we can now say the theory was incorrect and our telescopes have not failed us,” lead researcher and Curtin research fellow Dr Paul Hancock said. The technique used to create the ultra-sensitive image was recently published in The Astrophysical Journal. It allowed for the stacking of 200 separate observations on top of each other to re-create the image of a gamma-ray burst in much better quality – yet, no trace of a radio afterglow was found. “In our research paper we argue that there

must be two distinct types of gamma-ray burst, likely linked to differences in the magnetic field of the exploding star,” Dr Hancock said. “Gamma-ray bursts are thought to mark the birth of a Black Hole or Neutron Star – both of which have super-dense cores. But Neutron Stars have such strong magnetic fields (a million times stronger than those of Black Holes) that producing gamma-rays are more difficult. “We think that those stars that collapse to form a Neutron Star have energy left over to produce the radio afterglow whereas those that become Black Holes put all their energy into one final powerful gamma-ray flash.” New work is underway to test the team’s theory and to see if there are other subtle ways in which the two types of bursts differ. “We now have to take a whole new look at gamma-ray bursts – so far this work has shown that being wrong is sometimes more interesting than being right,” Dr Hancock said. Telescope facilities such as the Australia Telescope Compact Array in northern New South Wales and the Karl Jansky Very Large Array in the US both have observing programs to search for gamma-ray burst afterglows and have been recently upgraded to increase their sensitivity. The research report can be found at http://arxiv.org/abs/1308.4766 Contacts and sources: Megan Meates, Curtin University, Source: Article, Image

Read More........→December 27, 2013

Peer Into A Simulated Stellar-Mass Black Hole

A new study by astronomers at NASA, Johns Hopkins University and Rochester Institute of Technology confirms long-held suspicions about how stellar-mass black holes produce their highest-energy light. “We’re accurately representing the real object and calculating the light an astronomer would actually see,” says Scott Noble, associate research scientist in RIT’s Center for Computational Relativity and Gravitation. “This is a first-of-a-kind calculation where we actually carry out all the pieces together. We start with the equations we expect the system to follow, and we solve those full equations on a supercomputer. That gives us the data with which we can then make the predictions of the X-ray spectrum.” Lead researcher Jeremy Schnittman, an astrophysicist at NASA’s Goddard Space Flight Center, says the study looks at one of the most extreme physical environments in the universe: “Our work traces the complex motions, particle interactions and turbulent magnetic fields in billion-degree gas on the threshold of a black hole.” This animation of supercomputer data takes you to the inner zone of the accretion disk of a stellar-mass black hole. Gas heated to 20 million degrees Fahrenheit as it spirals toward the black hole glows in low-energy, or soft, X-rays. Just before the gas plunges to the center, its orbital motion is approaching the speed of light. X-rays up to hundreds of times more powerful (“harder”) than those in the disk arise from the corona, a region of tenuous and much hotter gas around the disk.

Credit: NASA’s Goddard Space Flight Center

Coronal temperatures reach billions of degrees.  By analyzing a supercomputer simulation of gas flowing into a black hole, the team finds they can reproduce a range of important X-ray features long observed in active black holes. “We’ve predicted and come to the same evidence that the observers have,” Noble says. “This is very encouraging because it says we actually understand what’s going on. If we made all the correct steps and we saw a totally different answer, we’d have to rethink what our model is.” Scott Noble, associate research scientist in RIT’s Center for Computational Relativity and Gravitation

Gas falling toward a black hole initially orbits around it and then accumulates into a flattened disk. The gas stored in this disk gradually spirals inward and becomes compressed and heated as it nears the center. Ultimately reaching temperatures up to 20 million degrees Fahrenheit (12 million C) — some 2,000 times hotter than the sun’s surface — the gas shines brightly in low-energy, or soft, X-rays. For more than 40 years, however, observations show that black holes also produce considerable amounts of “hard” X-rays, light with energy 10 to hundreds of times greater than soft X-rays. This higher-energy light implies the presence of correspondingly hotter gas, with temperatures reaching billions of degrees. The new study bridges the gap between theory and observation, demonstrating that both hard and soft X-rays inevitably arise from gas spiraling toward a black hole. Working with Noble and Julian Krolik, a professor at Johns Hopkins, Schnittman developed a process for modeling the inner region of a black hole’s accretion disk, tracking the emission and movement of X-rays, and comparing the results to observations of real black holes. Noble developed a computer simulation solving all of the equations governing the complex motion of inflowing gas and its associated magnetic fields near an accreting black hole. The rising temperature, density and speed of the infalling gas dramatically amplify magnetic fields threading through the disk, which then exert additional influence on the gas. The result is a turbulent froth orbiting the black hole at speeds approaching the speed of light. The calculations simultaneously tracked the fluid, electrical and magnetic properties of the gas while also taking into account Einstein’s theory of relativity. Running on the Ranger supercomputer at the Texas Advanced Computing Center located at the University of Texas in Austin, Noble's simulation used 960 of Ranger’s nearly 63,000 central processing units and took 27 days to complete. Over the years, improved X-ray observations provided mounting evidence that hard X-rays originated in a hot, tenuous corona above the disk, a structure analogous to the hot corona that surrounds the sun. “Astronomers also expected that the disk supported strong magnetic fields and hoped that these fields might bubble up out of it, creating the corona,” Noble says. “But no one knew for sure if this really happened and, if it did, whether the X-rays produced would match what we observe.” Using the data generated by Noble’s simulation, Schnittman and Krolik developed tools to track how X-rays were emitted, absorbed and scattered throughout both the accretion disk and the corona region. Combined, they demonstrate for the first time a direct connection between magnetic turbulence in the disk, the formation of a billion-degree corona, and the production of hard X-rays around an actively “feeding” black hole. Results from the study, “X-ray Spectra from Magnetohydrodynamic Simulations of Accreting Black Holes,” were published in the June 1 issue of The Astrophysical Journal (ApJ, 769, 156). In the corona, electrons and other particles move at appreciable fractions of the speed of light. When a low-energy X-ray from the disk travels through this region, it may collide with one of the fast-moving particles. The impact greatly increases the X-ray’s energy through a process known as inverse Compton scattering. “Black holes are truly exotic, with extraordinarily high temperatures, incredibly rapid motions and gravity exhibiting the full weirdness of general relativity,” Krolik says. “But our calculations show we can understand a lot about them using only standard physics principles.” The study was based on a non-rotating black hole. The researchers are extending the results to spinning black holes, where rotation pulls the inner edge of the disk further inward and conditions become even more extreme. They also plan a detailed comparison of their results to the wealth of X-ray observations now archived by NASA and other institutions. Black holes are the densest objects known. Stellar-mass black holes form when massive stars run out of fuel and collapse, crushing up to 20 times the sun’s mass into compact objects less than 75 miles (120 kilometers) wide. Contacts and sources: Susan Gawlowicz, Rochester Institute of Technology, Source: Nano Patents And Innovations

Read More........→June 17, 2013

Celestial Fireworks When Milky Way's Giant Black Hole Swallowed A Satellite Galaxy

Julie Turner, Vanderbilt University

These days the core of the Milky Way galaxy is a pretty tame place...cosmically speaking. The galactic black hole at the center is a sleeping giant. Existing stars are peacefully circling. Although conditions are favorable, there doesn’t even seem to be much new star formation going on. But there is growing evidence that several million years ago the galactic center was the site of all manner of celestial fireworks. A pair of assistant professors – Kelly Holley-Bockelmann at Vanderbilt and Tamara Bogdanović at Georgia Institute of Technology – have come up with an explanation that fits these “forensic” clues. Artist's illustration of a satellite galaxy on a collision course with the galactic black hole. Writing in the March 6 issue of the Monthly Notices of the Royal Astronomical Society, the astronomers describe how a single event – a violent collision and merger between the galactic black hole and an intermediate-sized black hole in one of the small “satellite galaxies” that circle the Milky Way – could have produced the features that point to a more violent past for the galactic core. “Tamara and I had just attended an astronomy conference in Aspen, Colorado, where several of these new observations were announced,” said Holley-Bockelmann. “It was January 2010 and a snow storm had closed the airport. We decided to rent a car to drive to Denver. As we drove through the storm, we pieced together the clues from the conference and realized that a single catastrophic event – the collision between two black holes about 10 million years ago - could explain all the new evidence.” The most dramatic of these extraordinary clues are the Fermi bubbles. These giant lobes of high-energy radiation - caused by particles moving nearly the speed of light - extend some 30,000 light years above and below the Milky Way center. If they were glowing in visible light they would fill about half of the night sky. But they radiate X-ray and gamma-ray light, so you need X-ray vision to see them. The discovery was reported by astronomers at the Harvard-Smithsonian Center for Astrophysics. Another puzzling characteristic of the GC, the astronomer’s abbreviation for the galactic center, is the fact that it contains the three most massive clusters of young stars in the entire galaxy. The Central, Arches and Quintuplet clusters each contain hundreds of young, hot stars that are much larger than the Sun. These stars typically burn out in “only” a few million years because of their extreme brightness, so there had to have been a relatively recent burst of star formation at the GC. The supermassive black hole that dominates the center of the Milky Way weighs in at about four million solar masses and is roughly 40 light seconds in diameter: only nine times the size of the sun. Such an object produces intense gravitational tides. So astronomers were surprised to discover a number of clumps of bright new stars closer than three lights years from the black hole’s maw. It wouldn’t be that surprising if the stars were being sucked into the black hole, but they show every sign of having formed in place. For this to happen, the clouds of dust and gas that they formed from must have been exceptionally dense: 10,000 times thicker than the other molecular clouds in the GC. While there is an excess of young hot stars in the galactic core, there is also a surprising dearth of older stars. Theoretical models predict that the density of old stars should increase as you move closer to the black hole. Instead, there are very few old stars found within several light years of the sleeping giant. When she got home from the conference, Holley-Bockelmann recruited Vanderbilt graduate student Meagan Langto work on the problem with them. With the assistance of Pau Amaro-Seoane from the Max Planck Institute for Gravitational Physics in Germany, Alberto Sesana from the Institut de Ciències de l'Espai in Spain, and Vanderbilt Research Assistant Professor Manodeep Sinha, they came up with a theoretical model that fits the observations and makes some testable predictions. The scenario began about 13 billion years ago, when the path of one of the smaller satellite galaxies orbiting the Milky Way is diverted so that it began drifting inward toward the core. According to a recent study, this may have happened dozens of times in the lifetime of the Milky Way. As the satellite galaxy – a collection of stars and gas with an intermediate-sized black hole with a mass equal to about 10,000 suns – spiraled in, most of its mass was gradually stripped away, finally leaving the black hole and a handful of gravitationally bound stars. About 10 million years ago, the stripped down core of the satellite galaxy finally reached the galactic center. When two black holes merge, they first go through an elaborate dance. So the smaller black hole would have circled the galactic black hole for several million years before it was ultimately consumed. As the smaller black hole circled closer and closer, it would have churned up the dust and gas in the vicinity and pushed enough material into the galactic black hole in the process to produce the Fermi bubbles. The violent gravitational tides produced by the process could easily have compressed the molecular clouds in the core to the super densities required to produce the young stars that are now located on the central black hole’s doorstep. In addition, the vigorous churning would have swept out the existing stars from the area surrounding the massive central black hole. In fact, the astronomer’s model predicts that the black holes’ merger dance should have flung a large number of the missing old stars out into the galaxy at hyper velocities, thus explaining the absence of old stars immediately around the super-massive black hole. “The gravitational pull of the satellite galaxy’s black hole could have carved nearly 1,000 stars out of the galactic center,” said Bogdanović. “Those stars should still be racing through space, about 10,000 light years away from their original orbits.” It should be possible to detect these stars with large surveys like the Sloan Digital Sky Survey because these stars would be traveling at much higher velocities than stars that have not undergone this type of interaction. So discovery of a large number of "high velocity stars" racing outward through the galaxy would strongly support the proposed scenario of the Milky Way and satellite galaxy merger. The research was supported by National Science Foundation Career Grant AST-0847696 and National Aviation and Space Administration grants NNX08AG74G and PF9-00061 as well as an NSF Graduate Research Fellowship. Contacts and sources: Vanderbilt Univerity, Citation: Monthly Notices of the Royal Astronomical Society, Source: Nano Patents And Innovations

Read More........→March 05, 2013