The neutralino in supersymmetric models with an extended Higgs
sector (NMSSM) can be naturally very light and difficult to discover by
direct dark matter detection experiments. Indirect detection rates,
however, are generically larger with respect to the standard case. We
explore the expected signals in neutrino telescopes, and in space-based
gamma-ray and antimatter search experiments. A potentially light CP-odd
Higgs boson exchange, can enhance the radiative modes for neutralino
pair annihilation into two photons, making the possibility of the
detection of a monochromatic gamma-ray line within the NMSSM more
promising than in the MSSM.
Although a neutralino in the MeV mass range could also account for the
511 KeV emission from the Galactic Center, measurements of the diffuse
radiation disfavor this scenario. Alternatively,
we will show that a network of superconducting cosmic strings can be at
the origin of the required positron flux.