Tail emission of prompt gamma-ray burst jets

Tail emission of the prompt Gamma-Ray Burst (GRB) is discussed using a multiple emitting sub-shell model which can reproduce the observed roughly monotonic decay. The global decay slope of the tail is not so much affected by the local angular inhomogeneity but affected by the global sub-shell energy distribution. The fact that steepening GRB tail breaks appeared in some events prefers the structured jets. If the angular size of the emitting sub-shell is around 0.01-0.02 rad, some bumps or fluctuations appear in the tail emission observed frequently in long GRBs.