INTEGRAL, eROSITA and Voyager Constraints on Light Bosonic Dark Matter: ALPs, Dark Photons, Scalars, $B-L$ and $L_{i}-L_{j}$ Vectors

TL;DR

This paper constrains various light bosonic dark matter models using observations from INTEGRAL, eROSITA, and Voyager, setting new limits on their decay properties across different mass ranges.

Contribution

It provides a comprehensive analysis of dark matter decay constraints from multiple astrophysical observations for several well-motivated models.

Findings

511 keV line data sets leading constraints below 1 GeV

eROSITA X-ray data constrains 1-10 GeV mass range

Future 21 cm line observations forecasted to improve limits

Abstract

The decay of light bosonic dark matter particles can produce a bright electron/positron ($e^+e^-$) flux that can be strongly constrained by local Voyager observations of the direct $e^+e^-$ flux, as well as 511 keV Line and X-ray continuum observations of $e^+e^-$ emission. We carefully analyze the $e^+e^-$ yield and resulting cosmic-ray and X-ray spectra from theoretically well-motivated light dark matter models, including: (a) electrophilic axion-like particles, (b) dark photons, (c) scalars, and (d) $B-L$ and $L_{i}-L_{j}$ vector bosons. We use the morphology and spectrum of the INTEGRAL 511 keV line data, the eROSITA X-ray continuum spectrum and the Voyager $e^+e^-$ spectrum to constrain the decay lifetime and coupling of each dark matter model. We find that 511 keV observations typically set world-leading limits on bosonic dark matter decay below masses of $\sim$1 GeV, while eROSITA observations provide the strongest constraints in the range from 1--10 GeV. Finally, we forecast future limits from 21 cm line searches with next-generation HERA data.