  We present the computation of the loop-induced self-annihilation of dark
matter particles into two photons in the framework of the NMSSM. This process
is a theoretically clean observable with a "smoking-gun" signature but is
experimentally very challenging to detect. The rates were computed with the
help of the SloopS program, an automatic code initially designed for the
evaluation of processes at the one-loop level in the MSSM. We focused on a
light neutralino scenario and discuss how the signal can be enhanced in the
NMSSM with respect to the MSSM and then compared with the present limits given
by the dedicated search of the FERMI-LAT satellite on the monochromatic gamma
lines.
