E. Quasi-Thermal Comptonization
Ghisellini and Celotti
[124]
suggested that the prompt GRB
emission arises in a quasi-thermal Comptonization process. In
their model the optical depth within the emitting region (of
internal shocks) is of order unity leading to a copious pair
production. The system is optically thick to synchrotron emission.
The self-absorbed synchrotron emission is the seed for an Inverse
Compton emission produced by the pairs. The effective Compton
paramter in the new system,
, is:
![]() |
(38) |
where T' is the effective temperature of the pair and
is
the total cross section for scattering. The pairs act as a
thermostat controlling the effective temperature within the
emitting region to 30-300 kev
[399,
400]. The
resulting spectrum from this model is a flat spectrum
F
0 between the
h
sa
and
kT'
[124].
The spectrum will evolve rapidly
during the burst while the pairs are being created and the
effective temperature decreases.