Could GRB 060614 and Its Presumed Host Galaxy Be a Chance Superposition?

Abstract

The lack of an observed supernova associated with GRB 060614 appears to require a new paradigm for the formation of (a subset of) long-duration GRBs. This requirement is based on the presumed low redshift of the burst, which was inferred from the spatial coincidence of the afterglow with a galaxy. We explore z p 0.125 the possibility that this low-redshift galaxy is a chance superposition along the line of sight to GRB 060614. We examine the galaxy distribution of the field of GRB 060614 and find that the probability of a chance association with a galaxy at least as bright as the putative host is only ∼0.5%–1.9%. However, for the current ensemble of ≈180 Swift GRBs, it is likely that several such coincidences have occurred, and given the “nonstandard” nature of GRB 060614 it is not implausible that this is one such occurrence. Thus, the conclusion that GRB 060614 requires a revision to the formation paradigm for long-duration GRBs should be approached with caution.