Title: Some clues to the progenitors of afterglows of Gamma-Ray Burst: the most luminous events in the Universe

Dr. Ram Sagar
ARIES, India

Multi-wavelength follow-up of Gamma-Ray Burst (GRB) afterglows has revolutionized GRB astronomy in recent years, yielding a wealth of information about the nature and origin of GRBs. One of the most important clues to the origin of GRBs is the total amount of energy released in the event. Optical observations have helped to derive this important quantity in a number of cases by setting the distance scale through measurement of redshift, and by determining the degree of collimation of the initial emission. We started the optical observations of long duration GRB with 1 meter class telescope at Nainital in January 1999 under a long term research program in collaboration with astronomers from all over the globe including India.
Multi-wavelength follow-up observations of GRB afterglows obtained so far, though they are mostly after few hours of the burst, clearly indicate that long duration GRBs are produced from stellar-like systems e.g. merging remnants or explosions of massive stars. However, the clues about the origin of short duration, hard GRBs indicate a different origin for them. Present scenario of both types of GRBs shall be discussed during the presentation.

UT Arlington Physics