Dark matter, neutron stars and strange quark matter

The energy release due to neutralino WIMP self-annihilation in the thermalization volume inside a compact object is shown to be comparable to the energy needed to create a long-lived lump of strange quark matter, or strangelet, for WIMP masses above a few GeV. Since strange matter is the most stable state of matter, accretion of self-annihilating dark matter onto neutron stars provides a mechanism to seed compact objects with lumps of strange quark matter and this effect may trigger a conversion of most of the star into a strange star. Using an energy estimate based on the Fermi gas model combined with the MIT bag model for the long-lived strangelet, a new limit on the possible values of the WIMP mass can be set that is competitive with those from direct searches. Our limit is especially important for subdominant species of massive neutralinos.