Updated bounds on Axion-Like Particle Dark Matter with the optical MUSE-Faint survey

Abstract: Bounds are derived on the axion-like particle (ALP) to two-photon coupling in the mass range $2.65-5.27$ eV. The bounds are obtained by searching for the signal from ALP decay in the Multi Unit Spectroscopic Explorer (MUSE) observations of five dwarf spheroidal galaxies, under the assumption that ALPs constitute the dark matter component of the haloes. These bounds are of the same order and improve on the robustness of those of Reference~\cite{Regis}, and currently represent the strongest bounds within the considered mass range.