GAMMA RAY BURSTS

An Enigma Being Unraveled

by

Alvaro De Rujula

Boston University and CERN

The best astrophysical accelerators are quasars and the “progenitors” of GRBs which, after decades of observations and scores of theories, we still do not understand. But, I shall argue, we now know quite well where GRBs come from, and we understand how their ``beams'' behave, as they make short pulses of gamma rays and long-duration X-ray, optical and radio “afterglows”. I shall argue that our understanding of these phenomena, based on the “Cannonball Model”, is unusually simple, precise and successful. The “sociology” of GRBs is interesting per se and, in this sense, the avatars of the Cannonball Model in confronting the generally accepted "fireball models" are also quite revealing.