Astrophysical limits on light NMSSM neutralinos

It was recently shown that light LSP neutralinos could be found in the framework of the Next-to-Minimal Supersymmetric Standard Model (NMSSM). These candidates would escape known particle physics constraints even though they are relatively light. We now investigate the astrophysical limits which can be set on these particles. We show, in particular, that the Fermi observation of dwarf spheroidal galaxies enable to constrain the parameter space associated with these candidates. Combined with the XENON100 experimental limits, our results illustrate the complementarity between direct and indirect searches for dark matter. Yet, our findings also suggest that probing light neutralinos in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) scenario will be very difficult because the sensitivity of both dark matter direct and indirect detection experiments would have to be improved by at least six orders of magnitude compared to present values in order to explore the entire parameter space. Finally, we show that the parameter space compatible with the CoGeNT signal (albeit disfavored by the XENON100 limit) is not excluded by gamma nor radio observations.