Testing the Viewing Angle Hypothesis for Short GRBs with LIGO Events

Abstract

It has been suggested that short gamma-ray bursts (GRBs) have shorter or undetectable spectral lags than longer GRBs because for the former, the observer's line of sight makes a larger angle with the GRB jet axis than it does for the latter. It is proposed that simultaneous gravitational-wave–short-GRB events could provide a simple test of this hypothesis. Multimessenger astronomy eventually may test whether event horizons are a necessary ingredient for GRBs.