2005/10/25 | γ射线爆发[Gamma Ray Burster]
类别(¤〖天文〗) | 评论(0) | 阅读(32) | 发表于 21:04
Gamma ray bursts were first detected by U. S. military Vela satellites launched in 1963 to monitor Soviet compliance with the nuclear test ban treaty. By 1967, it was realized that the bursts, which had energy densities from to cm-2, originated from space. However, this information was not made public until 1973 (Schwarzschild 1992). Gamma ray bursts occur a couple of times per day.

Three types of gamma ray bursters were identified by the BATSE instrument on the Compton Gamma Ray Observatory.

1. One large burst and a couple small ones within 10 s.
2. One large burst and a couple small ones in a fraction of a second.
3. Many large and small bursts over a minute.
The gamma ray bursters appear to have an isotropic distribution in space. The number distribution appears to go as at large L, but to fall off at low L, indicating a confined source distribution. Examination of old photographic plates has yielded visible bursts in regions where gamma ray burst have been found to arise (Sky & Telescope, Jan. 1991).
The Italian/Dutch BeppoSAX satellite, launched in 1996, provided the first rapid and accurate position for a gamma ray burster, allowing the source object to be observed from Palomar Observatory. A burst from May 8, 1997 was found to be a star-like object which was rapidly fading. This object was subsequently observed using one of the 10-meter Keck telescopes, and its redshift identified it as lying at a distance of several billion light-years. This means that, for a few seconds, the burster was more than a million times brighter than an entire galaxy. However, the nature of such a powerful and short-lived energy source still remains a mystery.
Pleurions have a possible connection with soft (low energy) repeating gamma ray bursters
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