  Long duration gamma ray bursts (GRBs) and X-ray flashes (XRFs) are produced
by highly- relativistic jets ejected in core-collapse supernova explosions. The
origin of short hard gamma-ray bursts (SHBs) has not been established. They may
be produced by highly relativistic jets ejected in various processes: mergers
of compact stellar objects; large-mass accretion episodes onto compact stars in
close binaries or onto intermediate-mass black holes in dense stellar regions;
phase transition of compact stars. Natural environments of such events are the
dense cores of globular clusters, superstar clusters and young supernova
remnants. We have used the cannonball model of GRBs to analyze all Swift SHBs
with a well-sampled X-ray afterglow. We show that their prompt gamma-ray
emission can be explained by inverse Compton scattering (ICS) of the
progenitor's glory light, and their extended soft emission component by ICS of
high density light or synchrotron radiation (SR) in a high density interstellar
medium within the cluster. The mechanism generating the afterglow is
synchrotron radiation outside the cluster. No associated supernova could be
detected in the low luminosity nearby GRBs 060614 and 060505. We interpret them
as SHBs seen relatively far off axis.
