Flares In Long And Short Gamma Ray Bursts
  The many similarities between the prompt emission pulses in gamma ray bursts
(GRBs) and X-ray flares during the fast decay and afterglow phases of GRBs
suggest a common origin. In the cannonball (CB) model of GRBs, this common
origin is mass accretion episodes of fall-back matter on a newly born compact
object. The prompt emission pulses are produced by a bipolar jet of highly
relativistic plasmoids (CBs) ejected in the early, major episodes of mass
accretion. As the accretion material is consumed, one may expect the engine's
activity to weaken. X-ray flares ending the prompt emission and during the
afterglow phase are produced in such delayed episodes of mass accretion. The
common engine, environment and radiation mechanisms (inverse Compton scattering
and synchrotron radiation) produce their observed similarities. Flares in both
long GRBs and short hard gamma ray bursts (SHBs) can also be produced by
bipolar ejections of CBs following a phase transition in compact objects due to
loss of angular momentum and/or cooling. Optical flares, however, are mostly
produced in collisions of CBs with massive stellar winds/ejecta or with density
bumps along their path. In this paper we show that the master formulae of the
CB model of GRBs and SHBs, which reproduce very well their prompt emission
pulses and their smooth afterglows, seem to reproduce also very well the
lightcurves and spectral evolution of the prominent X-ray and optical flares
that are well sampled.
