Chameleonic contribution to the Sunyaev-Zel’dovich radial profile of the Coma cluster

We constrain the chameleonic Sunyaev-Zel’dovich (CSZ) effect in the Coma cluster from measurements of the Coma radial profile presented in the WMAP 7-year results. The CSZ effect arises from the interaction of a scalar (or pseudoscalar) particle with the cosmic microwave background in the magnetic field of galaxy clusters. We combine this radial profile data with SZ measurements towards the center of the Coma cluster in different frequency bands, to find 𝛥⁢𝑇SZ,RJ⁡(0) =−410 ±50  𝜇⁢K and 𝛥⁢𝑇204 GHz
CSZ⁡(0) ≳−50  𝜇⁢K (at 95% confidence) for the thermal SZ and CSZ effects in the cluster, respectively. This leads to an estimated bound on the photon to scalar (or pseudoscalar) coupling strength of 𝑔eff ≲(8.3–37.6) ×10−10  GeV−1.