Astronomy and Astrophysics – Astrophysics
Scientific paper
2002-06-24
Astronomy and Astrophysics
Astrophysics
6 pages, talk at the XXIInd Moriond Astrophysics Meeting "The Gamma-Ray Universe", Les Arcs, France, March 9-12, 2002
Scientific paper
The standard afterglow model neglects the presence of the GRB prompt radiation ahead of the blast wave. In fact, the blast wave is dramatically influenced by the leading gamma-ray front which preaccelerates the ambient medium and loads it with electron-positron pairs. The front sweeps the medium outward with a high Lorentz factor and results in a spectacular effect: the GRB ejecta moves freely in a cavity behind its own radiation front. When the front expands sufficiently and gets diluted, a blast wave develops, and it does it differently from the standard model used before. The afterglow should initially appear as a steep rise of soft emission (from infrared to soft X-rays) at a time comparable to the prompt GRB duration and then the emission should quickly evolve to a normal X-ray afterglow. This may explain the prompt optical flash observed in GRB 990123 and allows one to infer the ejecta Lorentz factor in this burst: \Gamma=200. The effect of the gamma-ray front on the afterglow emission is especially pronounced if the GRB has a massive progenitor and the blast wave propagates in the progenitor wind. We emphasize the importance of early afterglow observations in soft bands, as they will allow one to test different progenitor models.
No associations
LandOfFree
Early GRB Afterglows Revisited does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Early GRB Afterglows Revisited, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Early GRB Afterglows Revisited will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-391968