A unified model of short and long gamma-ray bursts, X-ray rich gamma-ray bursts, and X-ray flashes

We propose a possible unified model of short and long gamma-ray bursts (GRBs), X-ray rich GRBs, and X-ray flashes. The jet of a GRB is assumed to consist of multiple sub-jets or sub-shells (i.e., an inhomogeneous jet model). The multiplicity of the sub-jets along a line of sight ns is an important parameter. If ns is large (≫1) the event looks like a long GRB, while if ns = 1, the event looks like a short GRB. Finally, when ns = 0, the event looks like an X-ray flash or an X-ray rich GRB. Furthermore, our model may also explain the bimodal distributions of T90 duration of BATSE-GRBs.