ALP Conversion and the Soft X-ray Excess in the Outskirts of the Coma Cluster

Understand

It was recently found that the soft X-ray excess in the center of the Coma cluster can be fitted by conversion of axion-like-particles (ALPs) of a cosmic axion background (CAB) to photons.

• We extend this analysis to the outskirts of Coma, including regions up to 5 Mpc from the center of the cluster.
• We extract the excess soft X-ray flux from ROSAT All-Sky Survey data and compare it to the expected flux from ALP to photon conversion of a CAB.
• The soft X-ray excess both in the center and the outskirts of Coma can be simultaneously fitted by ALP to photon conversion of a CAB.