  We discuss the GeV to TeV photon emission of gamma-ray bursts (GRBs) within
the refreshed shock and the continuous injection scenarios, motivated by the
observation of extended emission in a substantial fraction of short GRBs. In
the first model we assume that the central engine emits promptly material with
a range of Lorentz factors. When the fastest shell starts to decelerate, it
drives a forward shock into the ambient medium and a reverse shock in the
ejecta. These shocks are reenergized by the slower and later arriving material.
In the second model we assume that there is a continued ejection of material
over an extended time, and the continuously arriving new material keeps
reenergizing the shocks formed by the preceding shells of ejecta. We calculate
the synchrotron and synchrotron self-Compton radiation components for the
forward and reverse shocks and find that prospective and current GeV to TeV
range instruments such as CTA, HAWC, VERITAS, MAGIC and HESS have a good chance
to detect afterglows of short bursts with extended emission, assuming a
reasonable response time.

High Energy Astrophysical Phenomena