Detectable synchrotron radio emission may follow gamma-ray bursts (GRBs). A few robust inferences about physical conditions in bursts suffice to estimate the characteristics of this emission. The fluence and time variability of bursts, coupled with either of the popular distance scales (halo or cosmological), imply super-Eddington luminosities and hence relativistic ejecta. These ejecta sweep up interstellar matter in a shock front, and electrons accelerated in the shock will emit synchrotron photons in any nonzero magnetic field. This mechanism is similar to those believed responsible for the observed radio emission from supernova remnants and radio galaxies. For the brightest GRBs we estimate peak flux densities of milliJanskys. The time of peak radio emission depends on the distance scale; it follows the GRB by under a minute if the bursts are in the halo and by about a week if they are at cosmological distances.
Wednesday program listing