Dynamics of WIMPs in the solar system and implications for direct and indirect detection

TL;DR

This study uses numerical simulations to evaluate how bound WIMPs in the solar system influence detection rates, finding minimal impact on direct detection and low prospects for neutrino detection from Earth, but potential reduction in solar neutrino signals.

Contribution

It provides the first detailed numerical analysis of the bound WIMP population's properties and their impact on detection prospects, refining previous semi-analytic estimates.

Findings

Bound WIMP population increases direct detection rate by at most 1%.

Neutrino telescopes are unlikely to detect WIMP annihilation in Earth.

WIMP annihilation in the Sun may produce fewer neutrinos than previously estimated.

Abstract

Semi-analytic treatments of the evolution of orbits of weakly interacting massive particles (WIMPs) in the solar system suggest that the WIMPs bound to the solar system may enhance the direct detection rate relative to that of the unbound population by up to a factor of order unity, and boost the flux of neutrinos from WIMP annihilation in the Earth by up to two orders of magnitude. To test these important but uncertain results, we perform a suite of numerical orbit integrations to explore the properties of the bound WIMP population as a function of the WIMP mass and the scattering cross section with baryonic matter. For regions of WIMP parameter space presently allowed by experiments, we find that (i) the bound WIMP population enhances the direct detection rate by at most ~1% relative to the rate from unbound halo WIMPs; (ii) it is unlikely that planned km^3-scale neutrino telescopes will detect neutrinos from WIMP annihilation in the Earth; (iii) the event rate from neutrinos produced by WIMP annihilation in the Sun may be much smaller than implied by the usual calculations, which assume that WIMPs scattered onto bound orbits are rapidly thermalized in the Sun.