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R. Sari (Caltech)
Afterglow observations in the past few years have provided tremendous support for the fireball model. The physical conditions at late times (more than a few hours after the burst) are only sensitive to global properties of the burst, such as the total energy and the degree to which the outflow is collimated. However, more detailed information can be retrieved from observations within the first few minutes. During the early afterglow, emission from the explosion ejecta (rather than from the shocked surroundings), the so called reverse shock, dominates at radio and optical wavelengths. We will discuss the theoretical predictions for the very early afterglow, and show how early-time observations can tell us about the mass embedded in the explosion, the ambient density, the spatial uniformity of the explosion and the density close to the explosion site.
The author(s) of this abstract have provided an email address for comments about the abstract: sari@tapir.caltech.edu