Probing The Longest Dark Matter Lifetimes with the Line Emission Mapper

TL;DR

The paper forecasts the Line Emission Mapper's (LEM) unprecedented sensitivity to decaying dark matter, predicting it can detect extremely long dark matter lifetimes in the keV range, surpassing current limits.

Contribution

It provides the first forecast of LEM's sensitivity to dark matter decay signals, highlighting its potential to probe lifetimes beyond 10^{32} seconds.

Findings

LEM can detect dark matter decay lifetimes beyond 10^{32} seconds.

LEM's sensitivity surpasses current limits by several orders of magnitude.

First instrument capable of probing such long dark matter lifetimes.

Abstract

In the next decade, the proposed Line Emission Mapper (LEM) telescope concept is poised to revolutionize Galactic and extragalactic X-ray sensitivity. The instruments aboard LEM feature unprecedented eV scale energy resolution and an effective area of 1600 cm$^2$ at 0.5 keV. Such features are ideally suited to explore decaying dark matter candidates that predict X-ray signals, including axion-like particles and sterile neutrinos. We present the first forecast of LEM sensitivity to dark matter decays and find sensitivity to lifetimes beyond $\sim 10^{32}$ s in the keV range, surpassing current limits by several orders of magnitude. Notably, our results show that LEM will be the first ever instrument to probe such long dark matter lifetimes in any mass range for any decay channel.