Hubble breaks record for furthest supernova

Record-breaking supernova in the CANDELS Ultra Deep Survey

The NASA/ESA Hubble Space Telescope has broken the record in the quest to find the furthest supernova of the type used to measure cosmic distances. This supernova exploded more than 10 billion years ago (redshift 1.914), at a time the Universe was in its early formative years and stars were being born at a rapid rate. The supernova, designated SN UDS10Wil [1], belongs to a special class of exploding stars known as Type Ia supernovae. These bright beacons are prized by astronomers because they can be used as a yardstick for measuring cosmic distances, thereby yielding clues to the nature of dark

Record-breaking supernova in the CANDELS Ultra Deep Survey (compass and scale)

energy, the mysterious force accelerating the rate of expansion of the Universe. “This new distance record holder opens a window into the early Universe, offering important new insights into how these supernovae form,” said astronomer David O. Jones of The Johns Hopkins University in Baltimore, Md., lead author on the science paper detailing the discovery. “At that epoch, we can test theories about how reliable these detonations are for understanding the evolution of the Universe and its expansion.” One of the debates surrounding Type Ia supernovae is the nature of the fuse that ignites them. This latest discovery adds credence to one of two competing theories of how they explode. Although preliminary, the evidence favours the explosive merger of two burned out stars — small, dim, and dense stars known as white

The CANDELS Ultra Deep Survey (UDS)

dwarfs, the final state for stars like our Sun. The discovery was part of a three-year Hubble program called the CANDELS+CLASH Supernova Project, begun in 2010 [2]. This program aimed to survey faraway Type Ia supernovae to determine their distances and see if their behaviour has changed over the 13.8 billion years since the Big Bang, using the sharpness and versatility of Hubble’s Wide Field Camera 3. So far, CANDELS+CLASH has uncovered more than 100 supernovae of all types that exploded from 2.4 to over 10 billion years ago. The team has identified eight of these discoveries as Type Ia supernovae that exploded more than 9 billion years ago — including this new record-breaker, which, although only four percent older than the previous record holder, pushes the record roughly 350 million years further back in

Record-breaking supernova in the CANDELS Ultra Deep Survey: before, after, and difference

time [3]. The supernova team’s search technique involved taking multiple near-infrared images spaced roughly 50 days apart over the span of three years, looking for a supernova’s faint glow. After spotting SN UDS10Wil in December 2010, the CANDELS team then used the spectrometer on Hubble’s Wide Field Camera 3, along with the European Southern Observatory’s Very Large Telescope, to verify the supernova’s distance and to decode its light, hoping to find the unique signature of a Type Ia supernova. Finding remote supernovae opens up the possibility to measure the Universe’s accelerating expansion due to dark energy [4]. However, this is an area that is not fully understood — and nor are the origins of Type Ia supernovae. “This new result is a really exciting step forward in our study of supernovae and the distant Universe,” said team member Jens Hjorth of the Dark Cosmology Centre at the Niels Bohr Institute, University of Copenhagen. “We can begin to explore and understand the stars that cause these

After view of the record-breaking supernova in the CANDELS Ultra Deep Survey

violent explosions.” The team’s preliminary evidence shows a sharp decline in the rate of Type Ia supernova blasts between roughly 7.5 billion years ago and more than 10 billion years ago. This, combined with the discovery of such Type Ia supernovae so early in the Universe, suggests that the explosion mechanism is a merger between two white dwarfs. In the single white dwarf scenario — a pathway in which a white dwarf gradually feeds off a partnering normal star and explodes when it accretes too much mass — the rate of supernovae can be relatively high in the early Universe, because some of these systems can reach the point of explosion very quickly. The steep drop-off favours the double white dwarf mechanism, because it predicts that most stars in the early Universe are too young to become

Hubble in orbit

Type Ia supernovae. Knowing what triggers Type Ia supernovae will also show how quickly the Universe enriched itself with heavier elements, such as iron. These exploding stars produce about half of the iron in the Universe, the raw material for building planets, and life. The team’s results will appear in the 10 May 2013 issue of The Astrophysical Journal. Notes: [1] The supernova has been catalogued as SN UDS10Wil in the CANDEL-CLASH list. It has also been nicknamed SN Wilson, after the 28th U.S. president Woodrow Wilson. [2] This project searches for supernovae in near-infrared light and verifies their distances with spectroscopy. The supernova search draws on two large Hubble programs studying distant galaxies and galaxy clusters: the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) and the Cluster Lensing and Supernova Survey with Hubble (CLASH). [3] The previous record holder was recently announced by a team that identified a supernova that exploded around 9 billion years ago (redshift 1.7). The paper was published in The Astrophysical Journal, available here:http://iopscience.iop.org/0004-637X/763/1/35 [4] It has been known since the late 1920s that distant galaxies appear to be moving away from us with a speed that is proportional to their distance. Edwin Hubble and Georges Lemaître were the first to infer that this implied the whole Universe is expanding. In 2011, the Nobel Prize in Physics was awarded to the teams of astronomers that discovered, using Type Ia supernovae, that this expansion is actually accelerating (ann11069) — Adam Riess of Johns Hopkins University, Saul Perlmutter of the University of California at Berkeley, and Brian Schmidt of the Australian National University in Canberra. This acceleration is attributed to dark energy, whose nature is unknown. Notes for editors: The Hubble Space Telescope is a project of international cooperation between ESA and NASA. The research is presented in a paper entitled “The Discovery of the Most Distant Known Type Ia Supernova at Redshift 1.914”, accepted for publication in 10 May 2013 issue of The Astrophysical Journal. The international team of astronomers in this study consists of: D. O. Jones (Johns Hopkins University, USA), S. A. Rodney (Johns Hopkins University, USA; Hubble Fellow), A. G. Riess (Johns Hopkins University, USA; Space Telescope Science Institute, USA), B. Mobasher (University of California, USA), T. Dahlen (Space Telescope Science Institute, USA), C. McCully (The State University of New Jersey, USA), T. F. Frederiksen (University of Copenhagen, Denmark), S. Casertano (Space Telescope Science Institute, USA), J. Hjorth (University of Copenhagen, Denmark), C. R. Keeton (The State University of New Jersey, USA), A. Koekemoer (Space Telescope Science Institute, USA), L. Strolger (Western Kentucky University, USA), T. G. Wiklind (Joint ALMA Observatory, ESO, Chile), P. Challis (Harvard/Smithsonian Center for Astrophysics, USA), O. Graur (Tel-Aviv University, Israel; American Museum of Natural History, USA), B. Hayden (University of Notre Dame, USA), B. Patel (The State University of New Jersey, USA), B. J. Weiner (University of Arizona, USA), A. V. Filippenko (University of California, USA), P. Garnavich (University of Notre Dame, USA), S. W. Jha (The State University of New Jersey, USA), R. P. Kirshner (Harvard/Smithsonian Center for Astrophysics, USA), S. M. Faber (University of California, USA), H. C. Ferguson (Space Telescope Science Institute, USA), N. A. Grogin (Space Telescope Science Institute, USA), and D. Kocevski (Harvard/Smithsonian Center for Astrophysics, USA). Links: Images of Hubble: http://www.spacetelescope.org/images/archive/category/spacecraft/, NASA press release: http://hubblesite.org/newscenter/archive/releases/2013/11/, CANDELS survey: http://candels.ucolick.org/, CLASH collaboration: http://www.stsci.edu/~postman/CLASH/, Research paper: http://www.spacetelescope.org/static/archives/releases/science_papers/heic1306.pdf, Images, Text, Credits: NASA, ESA, A. Riess, Z. Levay (STScI and JHU), and D. Jones and S. Rodney (JHU) / S. Faber (University of California, Santa Cruz), H. Ferguson (STScI), and the CANDELS team. Greetings, Orbiter.ch, Source: Orbiter.ch Space News

Read More........→April 07, 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