Gamma-ray burst
hideGamma-ray bursts (GRBs) are flashes of gamma rays associated with extremely energetic explosions in distant galaxies. They are the most luminous electromagnetic events occurring in the universe. Bursts can last from milliseconds to nearly an hour, although a typical burst lasts a few seconds. The initial burst is usually followed by a longer-lived "afterglow" emitting at longer wavelengths (X-ray, ultraviolet, optical, infrared, and radio).
Most observed GRBs are believed to be a narrow beam of intense radiation released during a supernova event, as a rapidly rotating, high-mass star collapses to form a black hole. A subclass of GRBs (the "short" bursts) appear to originate from a different process, possibly the merger of binary neutron stars.
The sources of most GRBs are billions of light years away from Earth, implying that the explosions are both extremely energetic (a typical burst releases as much energy in a few seconds as the Sun will in its entire 10 billion year lifetime) and extremely rare (a few per galaxy per million years). All observed GRBs have originated from outside the Milky Way galaxy, although a related class of phenomena, soft gamma repeater flares, are associated with magnetars within the Milky Way. It has been hypothesized that a gamma-ray burst in the Milky Way could cause a mass extinction on Earth.
GRBs were first detected in 1967 by the Vela satellites, a series of satellites designed to detect covert nuclear weapons tests. Hundreds of theoretical models were proposed to explain these bursts in the years following their discovery, such as collisions between comets and neutron stars. Little information was available to verify these models until the 1997 detection of the first X-ray and optical afterglows and direct measurement of their redshifts using optical spectroscopy. These discoveries, and subsequent studies of the galaxies and supernovae associated with the bursts, clarified the distance and luminosity of GRBs, definitively placing them in distant galaxies and connecting long GRBs with the deaths of massive stars.
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News tagged with gamma ray burst
In a Galaxy Far, Far Away...
Nov 06, 2009 |
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(PhysOrg.com) -- Astronomers have published the discovery of the farthest known object in the cosmos: a star that exploded when the universe was only 630 million years old -- only 4.6% of its current age. ...
Fermi Telescope Detects Gamma-Ray From 'Star Factories' in Other Galaxies
Nov 02, 2009 |
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Nearby galaxies undergoing a furious pace of star formation also emit lots of gamma rays, say astronomers using NASA's Fermi Gamma-ray Space Telescope. Two so-called "starburst" galaxies, plus a satellite ...
Astronomers explore 'last blank space' on map of the Universe
Oct 28, 2009 |
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(PhysOrg.com) -- The most distant object ever discovered is described in this week's edition of the science journal Nature. Two international teams of astronomers report their observations of a gamma-ray burst ...
Blast from the Past Gives Clues About Early Universe
Oct 28, 2009 |
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(PhysOrg.com) -- Astronomers using the National Science Foundation's Very Large Array (VLA) radio telescope have gained tantalizing insights into the nature of the most distant object ever observed in the ...
Invading black holes explain cosmic flashes
Sep 18, 2009 |
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(PhysOrg.com) -- Black holes are invading stars, providing a radical explanation to bright flashes in the universe that are one of the biggest mysteries in astronomy today.
Keck Study Sheds New Light on "Dark" Gamma-ray Bursts
Jun 08, 2009 |
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Since its launch in 2004, NASA's Swift has detected more than 430 gamma-ray bursts. Roughly half of them are "dark" bursts that emit little or no visible light. Dense knots of dust in otherwise normal galaxies ...
Network creates virtual super-telescope
Jun 08, 2009 |
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Vast quantities of data are transferred in real time from telescopes around the world to a supercomputer in the Netherlands, where European researchers combine the information to create high-resolution images ...
Allen Telescope Array begins all-sky surveys
May 28, 2009 |
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(PhysOrg.com) -- With commissioning of the 42 radio dishes of the Allen Telescope Array (ATA) nearly complete, UC Berkeley astronomers are now embarking on several major radio astronomy projects, including daily surveys of ...
New Gamma-Ray Burst Smashes Cosmic Distance Record (w/Video)
Apr 28, 2009 |
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(PhysOrg.com) -- NASA's Swift satellite and an international team of astronomers have found a gamma-ray burst from a star that died when the universe was only 630 million years old, or less than five percent ...
Swift Satellite records early phase of gamma ray burst
Mar 02, 2009 |
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(PhysOrg.com) -- UK astronomers, using a telescope aboard the NASA Swift Satellite, have captured information from the early stages of a gamma ray burst - the most violent and luminous explosions occurring ...
11 billion year-old blast from the past captured by UWA Zadko Telescope
Jan 09, 2009 |
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(PhysOrg.com) -- Galileo Galilei, who recorded the first astronomical observations with a telescope 400 years ago, would be impressed. Just in time for the International Year of Astronomy, astronomers at The University of ...
Astronomers use gamma-ray burst to probe star formation in the early universe
Jan 06, 2009 |
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(PhysOrg.com) -- 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 ...
