Gamma-Ray Burst Afterglows: Two Post-Standard Effects

摘要

We discuss two "post-standard" effects in gamma-ray burst (GRB) afterglows. (1) Though synchrotron emission of the relativistic electrons is the canonical interpretation to the GRB afterglow broadband emission, some high energy spectral components also play an important role under certain conditions. It is found that the proton synchrotron emission and some other hadron-related emission components are usually not important in most circumstances, in contrast with some of the previous rough estimates. The synchrotron self-inverse Compton (IC) emission of the electrons, on the other hand, is found to be important in a large shock parameter space, and an extended (hours) IC-origin GeV afterglow for a typical (z = 1) GRB is predicted, which is readily detectable by the future mission, GLAST, if the shock parameters as inferred from the present afterglow fitting are typical among most long bursts. (2) In some types of the gamma-ray burst central engines, a significant energy input into the fireballs may in principle occur after the afterglow is set up, either in the form of some kinetic-energy-dominated shells or a Poynting-flux-dominated flow. Both cases are modeled, with distinct injection signatures that may bring us the information about the nature of the injection flow, or even the nature of the central engine.