Constraining eV-scale axion-like particle dark matter: insights from the M87 Galaxy

TL;DR

This study uses multi-wavelength observations of the M87 galaxy to set new constraints on eV-scale axion-like particle dark matter decay, improving existing bounds on their photon coupling in certain mass ranges.

Contribution

It provides the first multi-wavelength constraints on eV-scale ALP dark matter decay from the M87 galaxy, surpassing previous bounds in specific mass ranges.

Findings

Stronger bounds on ALP-photon coupling for 8-20 eV mass range.

Constraints derived from infrared to ultraviolet observations.

ALPs could constitute dark matter with decay signatures constrained.

Abstract

Axion-like particles (ALPs) can account for the observed dark matter (DM) of the Universe and if their masses are at the eV scale, they can decay into infrared, optical and ultraviolet photons with a decay lifetime larger than the age of the Universe.We analyze multi-wavelength data obtained from the central region of Messier 87 (M87) galaxy by several telescopes, such as, Swift, Astrosat, Kanata, Spitzer and International Ultraviolet Explorer in the infrared to ultraviolet frequencies ($\sim 2\times10^{14} \, {\rm Hz} - 3\times10^{15}$ Hz), to constrain the narrow emission lines indicative of the eV scale ALP DM decay. We derive constraints on the ALP coupling to two photons ($g_{a\gamma\gamma}$) for ALP mass range $2 \, {\rm eV} \lesssim m_a \lesssim 20 \, {\rm eV}$, assuming ALPs form the DM in the M87 halo. We find that our bounds on ALP-two-photon coupling can become stronger than the existing ones by an order of magnitude in the ALP mass range $8 \, {\rm eV} \lesssim m_a \lesssim 20 \, {\rm eV}$.