gamma-ray bursts

gamma-ray bursts

Intense flashes of hard X-rays or gamma rays, detected at energies up to one million electronvolts. They are of short duration (0.1–1000 seconds) and were discovered by US Air Force satellites in 1967 but not declassified until 1973. There are sharp temporal features in the burst time profile; this allows the measurement of differences in arrival times of wavefronts of the order of a few milliseconds over baselines separated by hundreds of light-seconds. For the strongest and most rapidly varying bursts, such measurements yield angular resolutions of the order of arc seconds. The most intense burst observed so far lies within the supernova remnant N49 in the Large Magellanic Cloud. The BATSE experiment on the Compton Gamma Ray Observatory has detected hundreds of γ-ray bursts, averaging about one per day. Measurements have revealed that the distribution of the bursts is consistent with isotropy: they are uniformly distributed across the sky. Their origin still remains a mystery. γ-ray emission lines in their spectra may be related to annihilation radiation redshifted by the strong gravitational field of a neutron star, and γ-ray absorption features to cyclotron absorption in intense magnetic fields. The rapid temporal structure, including the periodic emission, is generally assumed to point to neutron star origins for γ-ray bursts, although sources at cosmological distances cannot be ruled out. The most probable energy source is thought to be either gravitational or nuclear in origin.

gamma-ray bursts

[′gam·ə ‚rā ‚bərsts]
(astronomy)
Intense blasts of soft gamma rays of unknown origin, which range in duration from a tenth of a second to tens of seconds and occur several times a year from sources widely distributed over the sky.
References in periodicals archive ?
Following the merger of two neutron stars, the gamma-ray burst that is produced would get brighter for a short period of time, and then fade away, according to other observations of short gamma-ray bursts.
The telescope will be used for the study of the evolution of black holes, the use of pulsars for spacecraft navigation, and to search for gamma-ray bursts.
Gamma-ray bursts represent invaluable tracers of the conditions in distant galaxies and provide a unique means of measuring the contribution of the faintest and highest-redshift galaxies to stellar mass assembly, yet we still do not understand what their progenitor system is or what environmental in?
TEHRAN (FNA)- Researchers produced a record high number of electron-positron pairs, opening exciting opportunities to study extreme astrophysical processes, such as black holes and gamma-ray bursts.
Each year, astronomers observe several hundred of these explosions, known as gamma-ray bursts, but this marks the first time scientists have spotted a burst's remnant radiance before detecting the burst itself.
It remains the only satellite capable of precisely locating gamma-ray bursts -- the universe's most powerful explosions -- and monitoring them across a broad range of wavelengths using multiple instruments before they fade from view.
Farley Ferrante, a graduate student in SMU's Department of Physics, who monitored the observations along with two astronomers in Turkey and Hawaii, said gamma-ray bursts are believed to be the catastrophic collapse of a star at the end of its life.
Observations of one of the most powerful exploding stars ever recorded suggest that the standard model for gamma-ray bursts might be missing a piece of the puzzle, scientists report in papers published online November 21st in Science.
Gamma-ray bursts interest him because they're the most extreme explosions human beings know about, he said.
The most powerful explosions in the universe are brilliant flashes of light called gamma-ray bursts.
Gamma-ray bursts (GRBs) are powerful explosions occurring in distant galaxies that often signal the death of stars.
experiment, amongst others, high energy backgrounds and diffuse emissions including a report from the KASCADE experiment, gamma-ray bursts such as those observed in the "Pi in the Sky" experiment, a number of topics within the subject areas of black holes and neutron star systems, pulsars and magnetars, and an array of topics within the fields of shocks and particle acceleration.