A 3.55 keV line from $\text{DM}\to a\to \gamma$: predictions for cool-core and non-cool-core clusters

Joseph P. Conlon, Andrew J. Powell

We further study a scenario in which a 3.55 keV X-ray line arises from decay of dark matter to an axion-like particle (ALP), that subsequently converts to a photon in astrophysical…