Searching for Decaying and Annihilating Dark Matter with Line Intensity Mapping

TL;DR

Line intensity mapping offers a promising method to detect signals from decaying or annihilating dark matter by cross-correlating spectral line emissions with mass distribution, significantly improving sensitivity over current techniques.

Contribution

This paper proposes using line-intensity mapping to search for dark matter decay and annihilation signals, providing a new approach with potential sensitivity improvements of ten orders of magnitude.

Findings

Potential for ten orders of magnitude sensitivity improvement

Method to cross-correlate spectral lines with mass distribution

Feasibility of detecting dark matter decay/annihilation signals

Abstract

The purpose of line-intensity mapping (IM), an emerging tool for extragalactic astronomy and cosmology, is to measure the integrated emission along the line of sight from spectral lines emitted from galaxies and the intergalactic medium. The observed frequency of the line then provides a distance determination allowing the three-dimensional distribution of the emitters to be mapped. Here we discuss the possibility to use these measurements to seek radiative decays or annihilations from dark-matter particles. The photons from monoenergetic decays will be correlated with the mass distribution, which can be determined from galaxy surveys, weak-lensing surveys, or the IM mapping experiments themselves. We discuss how to seek this cross-correlation and then estimate the sensitivity of various IM experiments in the dark-matter mass-lifetime parameter space. We find prospects for improvements of ten orders of magnitude in sensitivity to decaying/annihilating dark matter in the frequency bands targeted for IM experiments.