Emission from Bow Shocks of Beamed Gamma-Ray Bursts

Beamed gamma-ray burst (GRB) sources produce a bow shock in their gaseous environment. The emitted flux from this bow shock may dominate over the direct emission from the jet for lines of sight that are outside the angular radius of the jet emission, Θb. The event rate for these lines of sight is increased by a factor of ~260(Θb/5°)-2. For typical GRB parameters, we find that the bow shock synchrotron emission from a jet of half-angle ~5° is visible out to tens of megaparsecs in the radio and hundreds of megaparsecs in the X-ray. If GRBs are linked to supernovae (SNe), studies of peculiar SNe in the local universe should reveal this nonthermal bow shock emission for weeks to months following the explosion. Roughly one out of ~103(Θb/5°)2 SNe should display nonthermal bow shock emission, assuming a SN rate of ~(100 yr)-1 per L* galaxy.