Probing Dark Matter-Neutrino Connection via Indirect Detection Experiments

Various evidence reveals that dark matter is a primary component of this universe. The amount of dark matter is known, but its identity is a mystery. To determine its properties, efforts to detect and produce dark matter are underway. Dark matter annihilations throughout the galaxy may produce photons, neutrinos, and cosmic rays. Neutrino and photon detectors may then indirectly detect dark matter by detecting these annihilation products. The annihilation rate, dark matter mass, and dark matter scattering rate off of matter affect the signals received at Earth. These signals can therefore probe the identity of dark matter, especially if dark matter is a well-motivated Weakly Interacting Massive Particle. Another mystery in particle physics is how neutrinos acquire mass. To probe the identity of dark matter, considering only the simplest models may not be wise because there are many mysteries to solve. To consider the mysteries of neutrino mass and the identity of dark matter at the same time is a promising strategy. There are well motivated reasons to tie the two sectors together, and unique signals arise. Three specific results have been obtained. First, the IceCube Neutrino Observatory\u27s ability to probe the unique annihilation channel to prompt neutrinos that may result when dark matter couples to neutrinos is competitive with direct detection, and is not highly dependent on annihilation rate if detecting neutrinos from dark matter that have been captured by the Sun. Second, detecting the neutrino mass hierarchy at IceCube by detecting the annihilation of a scalar dark matter particle that exists in the context of a type-II seesaw-neutrino may also be possible in the context of measurements by other experiments. Third, in a type-I-seesaw scenario where dark matter annihilates to a few-GeV-mass right-handed neutrino inside the Sun, the right-handed neutrino can later decay outside the Sun giving unique strong signals that could set stringent constraints on allowed parameter space

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

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.Comment: 11 pages, 7 figures, 1 tabl