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D. A. Frail (National Radio Astronomy Observatory)
Great strides have been made in the last five years towards understanding the once mysterious gamma-ray bursts. By studying their X-ray, optical and radio afterglows, we have been able to derive the energy of the explosion, the geometry of the outflow, the density structure of the circumburst medium, and the properties of their host galaxies. Although many questions remained unanswered, a basic picture is beginning to emerge in which long-duration gamma-ray bursts originate from the birth of a black hole, triggered by the core collapse of a massive star. The subsequent explosion, with a typical energy of 1051 erg, drives a highly collimated, ultra-relativistic shock in the circumburst medium with a density of order 1 cm-3. In this talk, I will illustrate how this progress has been achieved, emphasizing where radio observations have made key contributions.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.