Gamma-ray bursts - a puzzle being resolved

For a few seconds a gamma-ray burst (GRB) becomes the brightest object in the universe, over-shining the rest of the universe combined! Clearly, this reflects extreme conditions that are fascinating and worth exploring. The recent discovery of GRB afterglow have demonstrated that we are on the right track towards the resolution of this long standing puzzle. These observations have confirmed the relativistic fireball model (more specifically the internal-external shocks model). The prompt optical emission seen in GRB 990123 have demonstrated that GRBs involve ultra-relativistic motion. The breaks in the light curves of GRB 990123 and GRB 990510 and the peculiar light curves of GRB 980519 and GRB 980326 disclosed that these GRBs are beamed. I examine these recent developments and discuss their implications to the models of the source. I argue that the current understanding implies that GRBs signal the birth of stellar mass black holes. (C) 2000 Elsevier Science B.V. All rights reserved.