GeV emission from short Gamma-Ray Bursts: the case of GRB 081024B
  We investigate whether the high energy tail detected by the Fermi/LAT for the
short GRB 081024B can be caused by synchrotron and self-Compton emission in the
context of either the internal or external shock models. For the internal shock
scenario, we explore the possibility of generating the high energy photons
directly by means of the synchrotron process, or inverse Compton emission in
which target photons are synchrotron photons produced in internal shocks taking
place in a lately emitted shell (delayed internal shocks). In the external
shock scenario, we test whether the high energy tail can be an extension of the
afterglow synchrotron emission, or alternatively the inverse Compton component
associated with the afterglow synchrotron photons. For the internal shock
scenario, we conclude that only an inverse Compton component from delayed
internal shocks can explain the high energy tail that extends to the GeV range.
In the external shock scenario, we show that the high energy tail may be
interpreted as synchrotron afterglow emission, if the slow cooling phase starts
as early as a few seconds after the trigger. On the other hand, the observed
high energy tail is consistent with an inverse Compton component of the
afterglow in the fast cooling regime.
