February 3, 2000 CfA Colloquium

Title: Gamma-Ray Bursts and Their Afterglows: Some Recent Developments

Speaker: Peter Meszaros

Abstract: Major advances have been made in the field of gamma-ray bursts in the last several years. The discovery of X-ray, optical and radio afterglows has made possible the identification of host galaxies at cosmological distances, the corresponding energy release inferred placing these among the most energetic events in the Universe. They are thought to be the outcome of a cataclysmic stellar collapse or merger leading to a relativistically expanding fireball, in which particles are accelerated at shocks producing nonthermal radiation. We discuss the theoretical predictions of the fireball shock model and how they compare to observations. Some of the new issues being raised by the recent observations concern the amount of the collimation of the outflow and its implications for the energetics, the production of prompt bright flashes at wavelenghts much longer than gamma-rays, the time structure of the afterglow, its dependence on the central engine or progenitor system behavior, and the role of the environment on the afterglow. We also discuss the prospects for future observational advances with HETE and Swift.

Reference for students:

Lunch on Thursday 2/3 at 12:00 noon in the classroom (A-101)