Dark Matter Decay to a Photon and a Neutrino: the Double Monochromatic Smoking Gun Scenario

TL;DR

This paper explores a potential double monochromatic signature from dark matter decay into gamma rays and neutrinos, proposing a correlated detection method that could serve as a definitive evidence for dark matter.

Contribution

It systematically analyzes effective operators inducing simultaneous gamma and neutrino lines from dark matter decay, including three-body final states, and discusses their observational prospects.

Findings

Dark matter decay can produce correlated gamma and neutrino lines.

Three-body decay channels can generate additional detectable spectral features.

Current bounds allow for the possibility of observing the double line signature.

Abstract

In the energy range from few TeV to 25 TeV, upper bounds on the dark matter decay rate into high energy monochromatic neutrinos have recently become comparable to those on monochromatic gamma-ray lines. This implies clear possibilities of a future double "smoking-gun" evidence for the dark matter particle, from the observation of both a gamma and a neutrino line at the same energy. In particular, we show that a scenario where both lines are induced from the same dark matter particle decay leads to correlations that can already be tested. We study this "double monochromatic" scenario by considering the complete list of lowest dimensional effective operators that could induce such a decay. Furthermore, we argue that, on top of lines from decays into two-body final states, three-body final states can also be highly relevant. In addition to producing a distinct hard photon spectrum, three-body final states also produce a line-like feature in the neutrino spectrum that can be searched for by neutrino telescopes.