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 many emitting sub-shells, that is called sub-jet emissions (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 = O, the event looks like an X-ray flash or an X-ray-rich GRB