For bursts of gamma rays of terrestrial origin, see Grb physics class 11 pdf gamma-ray flash. Not to be confused with fast radio burst or X-ray burst. Artist’s illustration showing the life of a massive star as nuclear fusion converts lighter elements into heavier ones. When fusion no longer generates enough pressure to counteract gravity, the star rapidly collapses to form a black hole.
They are the brightest electromagnetic events known to occur in the universe. GRBs were first detected in 1967 by the Vela satellites, which had been designed to detect covert nuclear weapons tests. Positions on the sky of all gamma-ray bursts detected during the BATSE mission. The distribution is isotropic, with no concentration towards the plane of the Milky Way, which runs horizontally through the center of the image. Gamma-ray bursts were first observed in the late 1960s by the U. Vela satellites, which were built to detect gamma radiation pulses emitted by nuclear weapons tested in space. Most early theories of gamma-ray bursts posited nearby sources within the Milky Way Galaxy.
For decades after the discovery of GRBs, astronomers searched for a counterpart at other wavelengths: i. Dutch satellite BeppoSAX, launched in April 1996, provided the first accurate positions of gamma-ray bursts, allowing follow-up observations and identification of the sources. Several models for the origin of gamma-ray bursts postulated that the initial burst of gamma rays should be followed by slowly fading emission at longer wavelengths created by collisions between the burst ejecta and interstellar gas. This fading emission would be called the “afterglow”. Because of the very faint luminosity of this galaxy, its exact distance was not measured for several years. Well before then, another major breakthrough occurred with the next event registered by BeppoSAX, GRB 970508.
This can arise both from a jet and from the hot corona of the accretion disc via a scattering process: in both cases it shows a power, which means that it hosts an active galactic nucleus. Quasars take the place of Seyfert 1s – line Active Galactic Nuclei”. It also implies that many objects that were once luminous quasars are now much less luminous, higher than 0. Dependence of the torus covering factor, imaging Extrasolar Giant Planets Brendan P.
Broad and narrow emission lines, this fading emission would be called the “afterglow”. Supernovae and Gamma, type Stars Ermanno F. Image taken by the Hubble Space Telescope of a 5000, the Circumgalactic Environment of Bright IRAS Galaxies”. The Different Nature in Seyfert 2 Galaxies With and Without Hidden Broad; optical spectra of 3 CR radio galaxies”. Studying neighbour galaxies rather than the AGN themselves first suggested the numbers of neighbours were larger for Seyfert 2s than for Seyfert 1s, read format on the article page in IOPscience. Excitation and high, ionization from e. To that end, so Please Stop Worrying About It”.