Lines and Boxes: Unmasking Dynamical Dark Matter through Correlations in the MeV Gamma-Ray Spectrum

TL;DR

This paper proposes a new gamma-ray spectral signature to identify non-minimal dark sectors like Dynamical Dark Matter, overcoming previous challenges of spectral smearing and enabling better detection prospects at MeV gamma-ray telescopes.

Contribution

It introduces an unambiguous spectral signature for non-minimal dark sectors that can be observed with future gamma-ray telescopes, improving detection capabilities.

Findings

Signature can distinguish DDM from minimal dark matter scenarios.

Spectral features are enhanced in the MeV gamma-ray range.

Potential for improved dark matter detection at future telescopes.

Abstract

Identifying signatures of dark matter at indirect-detection experiments is generally more challenging for scenarios involving non-minimal dark sectors such as Dynamical Dark Matter (DDM) than for scenarios involving a single dark particle. This additional difficulty arises because the partitioning of the total dark-matter abundance across an ensemble of different constituent particles with different masses tends to "smear" the injection spectra of photons and other cosmic-ray particles that are produced via dark-matter annihilation or decay. As a result, the imprints of the dark sector on these cosmic-ray flux spectra typically take the form of continuum features rather than sharp peaks or lines. In this paper, however, we identify an unambiguous signature of non-minimal dark sectors such as DDM which can overcome these issues and potentially be observed at gamma-ray telescopes operating in the MeV range. We discuss the specific situations in which this signature can arise, and demonstrate that this signature can be exploited in order to significantly enhance our ability to resolve the unique spectral features of DDM and other non-minimal dark sectors at future gamma-ray facilities.