Indirect Signals from Solar Dark Matter Annihilation to Long-lived Right-handed Neutrinos

TL;DR

This paper investigates how dark matter annihilations in the Sun producing long-lived right-handed neutrinos can generate detectable gamma-ray and neutrino signals, leading to stronger constraints on dark matter interactions than direct detection.

Contribution

It introduces a novel indirect detection method using delayed signals from long-lived right-handed neutrinos produced by solar dark matter annihilation.

Findings

Gamma-ray and neutrino signals can be used to constrain dark matter properties.

Combined bounds surpass direct detection limits for certain dark matter mass ranges.

Constraints on spin-independent and spin-dependent cross sections are significantly improved.

Abstract

We study indirect detection signals from solar annihilation of dark matter (DM) particles into light right-handed (RH) neutrinos with a mass in a $1-5$ GeV range. These RH neutrinos can have a sufficiently long lifetime to allow them to decay outside the Sun and their delayed decays can result in a signal in gamma rays from the otherwise `dark' solar direction, and also a neutrino signal that is not suppressed by the interactions with solar medium. We find that the latest Fermi-LAT and IceCube results place limits on the gamma ray and neutrino signals, respectively. Combined photon and neutrino bounds can constrain the spin-independent DM-nucleon elastic scattering cross section better than direct detection experiments for DM masses from 200 GeV up to several TeV. The bounds on spin-dependent scattering are also much tighter than the strongest limits from direct detection experiments.