Implications of a New Solar System Population of Neutralinos on Indirect Detection Rates

Abstract

Recently, a new Solar System population of weakly interacting massive particle (WIMP) dark matter has been proposed to exist. We investigate the implications of this population on indirect signals in neutrino telescopes (due to WIMP annihilations in the Earth) for the case when the WIMP is the lightest neutralino of the MSSM, the minimal supersymmetric extension of the standard model. The velocity distribution and capture rate of this new population is evaluated and the flux of neutrino-induced muons from the center of the Earth in neutrino telescopes is calculated. The strength of the signal is very sensitive to the velocity distribution of the new population. We analytically estimate this distribution using the approximate conservation of the component of the WIMP angular momentum orthogonal to the ecliptic plane. The non-linear problem of combining a fixed capture rate from the standard galactic WIMP population with one rising linearly with time from the new population to obtain the present-day annihilation rate in the Earth is also solved analytically. We show that the effects of the new population can be crucial for masses below around 150 GeV, where enhancements of the predicted muon flux from the center of the Earth by up to a factor of 100 compared to previously published estimates occur. As a result of the new WIMP population, the next generation of neutrino telescopes should be able to probe a much larger region of parameter space in the mass range 60-130 GeV.