Gamma-Ray Burst: New Observational Results and a Numerical Simulation
John Cannizzo
We present the new observational results on Gamma-ray burst and our numerical
simulation. The model is first unrestricted, 3D relativistic hydrodynamical
calculations of the blob of gas associated with the jet producing a gamma-ray
burst ``afterglow''. Our main findings are that
(i) gas ahead of the advancing blob does not accrete onto and merge with
the blob material but rather flows around the blob,
(ii) the decay light curve steepens at a time corresponding roughly to
1/gamma equals theta (in accord with earlier studies), and
(iii) the rate of decrease of the forward component of momentum in the
blob is well-fit by a simple model in which the gas in front of the
blob exerts a drag force on the blob, and the cross sectional area
of the blob increases quadratically with laboratory time (or
distance).