Indirect detection of a subdominant density component of cold dark matter

Abstract

We examine the detectability through indirect means of weakly interacting dark matter candidates that may constitute not all but only a subdominant component of galactic cold dark matter. We show that the possibility of indirect detection of neutralinos from their annihilations in the Earth and Sun is not severely hampered by decreasing neutralino relic density. Upward-going muon fluxes in underground detectors from neutralino annihilations in the Sun can remain above the threshold of detectability of 10 muons/km^2/yr for neutralinos composing 1% or more of the halo dark matter. Similarly, signals from neutralino annihilations in the Earth can also remain high for neutralino densities of 1% of the halo and actually would only be observable close to this low density for neutralinos lighter than 150 GeV. We also show that there are many models which simultaneously have high direct and indirect detection rates making some model discrimination possible if a signal is seen in any of the current dark matter searches.