 |
|
Integral expands our view of the gamma-ray sky
February 21, 2007Integral's latest survey of the gamma-ray universe continues to change the way astronomers think of the high-energy cosmos. With over seventy percent of the sky now observed by Integral, astronomers have been able to construct the largest catalogue yet of individual gamma-ray-emitting celestial objects. And there is no end in sight for the discoveries.
Integral is the European Space Agency's latest orbiting gamma-ray observatory. Ever since Integral began scientific operations in 2003, the project team has been devoting a substantial proportion of its observing time to a survey of the gamma-ray universe.
"The gamma-ray sky is notoriously variable and extremely unpredictable," says Anthony Dean, University of Southampton, UK, one of the original proposers of the Integral mission. Hence, the need for Integral's constant vigilance and an accurate catalogue of all gamma-ray sources. With this, astronomers can target individual gamma-ray objects for more detailed, study.
or the past three and a half years, Integral has been collecting survey data. At the end of every year, the data has been turned into a catalogue of sources.
During the first year, it concentrated on the regions close to the centre of our galaxy and found more than 120 sources. During the following year, Integral broadened its reach and found almost 100 more sources.
Now Integral has observed over 70 percent of the sky, with a total exposure time of 40 million seconds. A European team of astronomers led by Antony Bird, University of Southampton, UK, have turned all three years' worth of data into the third Integral catalogue of gamma-ray sources. It contains a total of 421 gamma-ray objects. Most have been identified as either binary stars in our Galaxy containing exotic objects such as black holes and neutron stars, or active galaxies, far away in space. But a puzzling quarter of sources remain unidentified so far.
"I think many of these will turn out to be either star systems enshrouded in dust and gas, or cataclysmic variable stars," says Dean. Integral observes in the gamma-ray band so it can see through the intervening material. It has demonstrated that it can discover sources obscured at other wavelengths.
One surprise has been the efficiency with which Integral has detected just one minor subclass of cataclysmic variable stars (CVs), the so-called intermediate polars. Initially astronomers were not sure that CVs would emit gamma rays. Indeed, Integral has already shown that only about one percent of them do. "At the moment, the reason why this should be is totally mysterious," says Dean.
As its surveys points further from our Galaxy, so Integral increasingly sees the active galaxies. These represent about a tenth of all galaxies and each one has some kind of extraordinary activity taking place in its core. It is widely accepted that this activity is driven by a gigantic black hole sucking matter out of existence.
Roman Krivonos, Max-Planck-Institute für Astrophysik, Germany, and colleagues have used the Integral survey to show that AGN are concentrated in the same places that ordinary galaxies are found. Whilst this is not an unexpected result, it is the first time such an AGN distribution has been seen at high-energies.
"Integral represents a milestone in gamma-ray astronomy," says Dean. Thirty years ago, NASA's Einstein observatory produced a catalogue of X-ray sources that became the standard reference document for all X-ray observatories - including ESA's XMM-Newton. "Integral is doing the same for gamma-ray astronomy," says Dean.
"We are in a golden age of gamma-ray astronomy," agrees Bird. And ESA's Integral is at the forefront of this brave new universe.
European Space Agency
During the first year, it concentrated on the regions close to the centre of our galaxy and found more than 120 sources. During the following year, Integral broadened its reach and found almost 100 more sources.
Now Integral has observed over 70 percent of the sky, with a total exposure time of 40 million seconds. A European team of astronomers led by Antony Bird, University of Southampton, UK, have turned all three years' worth of data into the third Integral catalogue of gamma-ray sources. It contains a total of 421 gamma-ray objects. Most have been identified as either binary stars in our Galaxy containing exotic objects such as black holes and neutron stars, or active galaxies, far away in space. But a puzzling quarter of sources remain unidentified so far.
"I think many of these will turn out to be either star systems enshrouded in dust and gas, or cataclysmic variable stars," says Dean. Integral observes in the gamma-ray band so it can see through the intervening material. It has demonstrated that it can discover sources obscured at other wavelengths.
One surprise has been the efficiency with which Integral has detected just one minor subclass of cataclysmic variable stars (CVs), the so-called intermediate polars. Initially astronomers were not sure that CVs would emit gamma rays. Indeed, Integral has already shown that only about one percent of them do. "At the moment, the reason why this should be is totally mysterious," says Dean.
As its surveys points further from our Galaxy, so Integral increasingly sees the active galaxies. These represent about a tenth of all galaxies and each one has some kind of extraordinary activity taking place in its core. It is widely accepted that this activity is driven by a gigantic black hole sucking matter out of existence.
Roman Krivonos, Max-Planck-Institute für Astrophysik, Germany, and colleagues have used the Integral survey to show that AGN are concentrated in the same places that ordinary galaxies are found. Whilst this is not an unexpected result, it is the first time such an AGN distribution has been seen at high-energies.
"Integral represents a milestone in gamma-ray astronomy," says Dean. Thirty years ago, NASA's Einstein observatory produced a catalogue of X-ray sources that became the standard reference document for all X-ray observatories - including ESA's XMM-Newton. "Integral is doing the same for gamma-ray astronomy," says Dean.
"We are in a golden age of gamma-ray astronomy," agrees Bird. And ESA's Integral is at the forefront of this brave new universe.
European Space Agency
Gamma-ray Burst Current Events and Gamma-ray Burst News RSSGamma-ray photon race ends in dead heat; Einstein wins this round
Racing across the universe for the last 7.3 billion years, two gamma-ray photons arrived at NASA's orbiting Fermi Gamma-ray Space Telescope within nine-tenths of a second of one another.
Fog lifted on 'dark' gamma-ray bursts, mysterious counterparts to bursts with an afterglow
Gamma-ray bursts, with their ability to pierce through gas and dust to shine brightly across the universe, are revealing areas of intense star formation and stellar death where astronomers have been unable to look - the dusty corners of otherwise dust-free galaxies.
NASA's Swift, Fermi Probe Fireworks From a Flaring Gamma-Ray Star
Astronomers using NASA's Swift satellite and Fermi Gamma-ray Space Telescope are seeing frequent blasts from a stellar remnant 30,000 light-years away.
Astronomers use gamma-ray burst to probe star formation in the early universe
The brilliant afterglow of a powerful gamma-ray burst (GRB) has enabled astronomers to probe the star-forming environment of a distant galaxy, resulting in the first detection of molecular gas in a GRB host galaxy.
NASA's Swift Catches Farthest Ever Gamma-Ray Burst
NASA's Swift satellite has found the most distant gamma-ray burst ever detected. The blast, designated GRB 080913, arose from an exploding star 12.8 billion light-years away.
'Naked-eye' gamma-ray burst was aimed squarely at Earth
Data from satellites and observatories around the globe show a jet from a powerful stellar explosion witnessed March 19 was aimed almost directly at Earth.
The Double Firing Burst
Astronomers from around the world combined data from ground- and space-based telescopes to paint a detailed portrait of the brightest explosion ever seen. The observations reveal that the jets of the gamma-ray burst called GRB 080319B were aimed almost directly at the Earth.
Brightest stellar explosion heralds new type of long-distance astronomy
A flash of light that blinded even small telescopes six months ago was the brightest astronomical explosion ever observed - visible to the naked eye despite originating halfway across the universe.
The quiet explosion
A European-led team of astronomers are providing hints that a recent supernova may not be as normal as initially thought. Instead, the star that exploded is now understood to have collapsed into a black hole, producing a weak jet, typical of much more violent events, the so-called gamma-ray bursts.
UC Santa Cruz physicists eagerly await launch of NASA space telescope they helped build
When NASA launches its newest space observatory, physicists at the University of California, Santa Cruz, will be watching as the product of nearly 16 years of hard work blasts into orbit.
More Gamma-ray Burst Current Events and Gamma-ray Burst News Articles
 |
Exploding Superstars: Understanding Supernovae and Gamma-Ray Bursts (Springer Praxis Books / Popular Astronomy) by Alain Mazure (Author), Stéphane Basa (Author) In Exploding Superstars, Alain Mazure and Stephane Basa show how great stellar explosions have become extremely important in recent years to cosmologists trying to understand the evolution of our universe since the Big Bang and the scale of that universe. Recently supernovae and gamma-ray bursters have been used, for example, as "standard candles," illuminating their immediate environs like searchlights and allowing us to study the cosmos between them and us. In the first three chapters the authors briefly review the great explosions that will form the subject matter of the book--namely, supernovae and gamma-ray bursters. They describe the very early universe, after the Big Bang, and then how "the lights came on all over the universe as the very first stars began to... |
 |
Toward an Understanding of the Progenitors of Gamma-Ray Bursts by Joshua S. Bloom (Author) The various possibilities for the origin ("progenitors") of gamma-ray bursts (GRBs) manifest in differing observable properties. Through deep spectroscopic and high-resolution imaging observations of some GRB hosts, I demonstrate that well-localized long-duration GRBs are connected with otherwise normal star-forming galaxies at moderate redshifts of order unity. Using high-mass binary stellar population synthesis models, I quantify the expected spatial extent around galaxies of coalescing neutron stars, one of the leading contenders for GRB progenitors. I then test this scenario by examining the offset distribution of GRBs about their apparent hosts making extensive use of ground-based optical data from Keck and Palomar and space-based imaging from the Hubble Space Telescope. The offset... |
 |
Gamma-Ray Burst: Sixth Huntsville Symposium, Huntsville (AIP Conference Proceedings / Astronomy and Astrophysics) by Charles Meegan (Editor), Chryssa Kouveliotou (Editor), Neil Gehrels (Editor) This was a technical symposium for astrophysicists working on gamma-ray bursts. It included discussions on the latest theoretical and experimental research on this topic, as well as plans for the next generation of orbiting instrumentation. The proceedings will be useful for specialists in the area of gamma-ray burst astronomy. |
 |
The Biggest Bangs: The Mystery of Gamma-Ray Bursts, the Most Violent Explosions in the Universe by Jonathan I. Katz (Author) Gamma-ray bursts are the most violent events since the birth of the universe. They are about ten times more energetic than the most powerful supernovae. At their peak, gamma-ray bursts are the brightest objects in space, about 100,000 times brighter than an entire galaxy. And yet until recently these titanic eruptions were the most mysterious events in astronomy. In The Biggest Bangs, astrophysicist Jonathan Katz offers a fascinating account of the scientific quest to unravel the mystery of these incredible phenomena. With an eye for colorful detail and a talent for translating scientific jargon into plain English, Katz ranges from the accidental discovery of gamma-ray bursts (by a Cold War satellite system monitoring the Nuclear Test Ban Treaty) to the frustrating but ultimately... |
 |
History -- Mega Disasters: Mega Gamma Ray Burst Also With: Creative Differences (Producer) Gamma ray bursts occur randomly and often. At times, they light up the reaches of deep space like fireworks. Just ten seconds' exposure to one would spell doom for Earth. And scientists at the University of Kansas believe such a thing may have happened 450 million years ago. The resulting destruction of the ozone layer and chemical smog might explain the mass extinction that ended the Ordovician Period. If it occurred once, what's to stop it from happening again? And what would be the result if such a devastating event happened today? This product is manufactured on demand using DVD-R recordable media. Amazon.com's standard return policy will apply. |
 |
Gamma-ray Burst 01-N (Primary Contributor) |
 |
Hubble Gamma Ray Burst Photo by Spaceimages |
 |
Gamma-Ray Bursts: The brightest explosions in the Universe (Springer Praxis Books / Astronomy and Planetary Sciences) by Gilbert Vedrenne (Author), Jean-Luc Atteia (Author) Since their discovery was first announced in 1973, gamma-ray bursts (GRBs) have been among the most fascination objects in the universe. While the initial mystery has gone, the fascination continues, sustained by the close connection linking GRBs with some of the most fundamental topics in modern astrophysics and cosmology. Both authors have been active in GRB observations for over two decades and have produced an outstanding account on both the history and the perspectives of GRB research. |
 |
Gamma-Ray Bursts: 30 Years of Discovery: Gamma-Ray Burst Symposium (AIP Conference Proceedings / Astronomy and Astrophysics) by E.E. Fenimore (Editor), M. Galasso (Editor) In the last thirty years, gamma-ray bursts have grown from an oddity to a central position in astrophysics. Not only are they the largest explosions since the big bang, capable of flooding most of the universe with gamma-rays, but their brilliance serves as a backlight that can illuminate the cosmos far deeper into the early universe than any other object. Their unpredictability has forced researchers to use extreme measures to observe them: completely autonomous satellites and robotic ground-based telescopes. Their bizarre physical properties have pushed us to develop new theories of astrophysical explosions. Topics include: global properties of GRBs; X-ray flashes; ultra-high energy gamma-rays, neutrinos, gravity waves; prompt emission and early afterglows; relativistic jets and... |
 |
Gamma-Ray Bursts in the Afterglow Era: Proceedings of the International Workshop Held in Rome, Italy, 17-20 October 2000 (ESO Astrophysics Symposia) by Enrico Costa (Editor), Filippo Frontera (Editor), Jens Hjorth (Editor) Proceedings of the International Workshop held October 17-20, 2001 in Rome, Italy. Reviews the research of the last two years and covers the global properties of GRBs, GRB afterglows, GRB host galaxies, cosmology using GRBs, and theories for GRBs and their afterglows. |
| © 2009 BrightSurf.com |