Pinning down inelastic dark matter in the Sun and in direct detection

TL;DR

This paper investigates the solar capture and detection prospects of inelastic dark matter, establishing bounds on capture rates and annihilation channels, and exploring how dual detection signals can reveal dark matter properties independently of astrophysical uncertainties.

Contribution

It introduces a method to set lower bounds on inelastic dark matter capture rates independent of astrophysical assumptions and analyzes how dual detection signals can determine dark matter characteristics.

Findings

Strong bounds on exothermic interactions, especially spin-dependent.

Dual detection signals can determine dark matter mass and splitting.

Isospin violation effects are discussed.

Abstract

We study the solar capture rate of inelastic dark matter with endothermic and/or exothermic interactions. By assuming that an inelastic dark matter signal will be observed in next generation direct detection experiments we can set a lower bound on the capture rate that is independent of the local dark matter density, the velocity distribution, the galactic escape velocity as well as the scattering cross section. In combination with upper limits from neutrino observatories we can place upper bounds on the annihilation channels leading to neutrinos. We find that, while endothermic scattering limits are weak in the isospin-conserving case, strong bounds may be set for exothermic interactions, in particular in the spin-dependent case. Furthermore, we study the implications of observing two direct detection signals, in which case one can halo-independently obtain the dark matter mass and the mass splitting, and disentangle the endothermic/exothermic nature of the scattering. Finally we discuss isospin violation.