NRAO/Socorro Colloquium Series:

Tsvi Piran

Hebrew University/Caltech


Gamma Ray Bursts: A Puzzle Being Resolved


Gamma Ray Bursts, short and intense bursts of gamma-rays from random directions in the sky, have puzzled astronomers since their serendipitous discovery in the late sixties. Recent progress led by observations carried out by the BATSE, BeppoSAX and HETE II satellites and by follow up x-ray, optical and radio observations on ground helped unveil some of the mystery involved. By now we know that (long duration) GRBs are associated with stellar collapse and we understand that the gamma-rays and the subsequent afterglow arise due to dissipation of ultra-relativistic outflow. However, many issues remain open. I will summarize the observations that have lead and have confirmed the current fireball model and the theoretical understanding of this phenomenon. I will focus on open questions, such as the nature of short bursts, the constitution of the relativistic outflow (baryonic flow or Poynting flux) and the angular structure of GRB jets. I will also discuss how these questions can be answered by the Swift satellite that was launched just three month ago and the crucial role of follow up radio observations.






Friday, 04 February 2005
11:00am

Array Operations Center Auditorium

Local Host: Dale A. Frail