Effective Theory of Dark Matter Decay into Monochromatic Photons and its Implications: Constraints from Associated Cosmic-Ray Emission

TL;DR

This paper explores how specific higher-dimensional operators can cause dark matter to decay into monochromatic photons, linking gamma-ray lines with cosmic-ray emissions to constrain dark matter properties.

Contribution

It identifies limited operators responsible for dark matter decay into photons and demonstrates their associated cosmic-ray emissions, enabling constraints on dark matter models.

Findings

Gamma-ray lines are always accompanied by cosmic-ray fluxes.

Observational bounds can constrain dark matter decay operators.

Potential to discriminate between operators based on cosmic-ray and gamma-ray data.

Abstract

We show that there exists only a quite limited number of higher dimensional operators which can naturally lead to a slow decay of dark matter particles into monochromatic photons. As each of these operators inevitably induces decays into particles other than photons, we show that the gamma-lines it induces are always accompanied by a continuum flux of cosmic rays. Hence constraints on cosmic-ray fluxes imply constraints on the intensity of gamma-lines and vice-versa. A comparison with up to date observational bounds shows the possibilities to observe or exclude cosmic rays associated to gamma-line emission, so that one could better determine the properties of the DM particle, possibly discriminating between some of the operators.