Sensitivity of JWST to eV-Scale Decaying Axion Dark Matter

TL;DR

This paper forecasts JWST's ability to detect or constrain eV-scale decaying axion dark matter through emission lines, providing new limits on axion properties in the Milky Way.

Contribution

It presents the first forecast of JWST's sensitivity to eV-scale axion decay signals using blank-sky observations, constraining axion-photon couplings and masses.

Findings

JWST can constrain axion-photon couplings down to 5.5 x 10^{-12} GeV^{-1}.

The study limits axion masses to below 0.2 eV for QCD axions.

Results will improve existing bounds on axion dark matter in the specified mass range.

Abstract

The recently-launched James Webb Space Telescope (JWST) can resolve eV-scale emission lines arising from dark matter (DM) decay. We forecast the end-of-mission sensitivity to the decay of axions, a leading DM candidate, in the Milky Way using the blank-sky observations expected during standard operations. Searching for unassociated emission lines will constrain axions in the mass range $0.18$ eV to $2.6$ eV with axion-photon couplings $g_{a\gamma\gamma}\gtrsim 5.5 \times 10^{-12}$ GeV$^{-1}$. In particular, these results will constrain astrophobic QCD axions to masses $\lesssim$ 0.2 eV.