The Chameleonic Contribution to the SZ Radial Profile of the Coma Cluster

TL;DR

This paper investigates the chameleonic Sunyaev--Zel'dovich effect in the Coma cluster using WMAP data, constraining the photon-scalar coupling strength and providing bounds on the effect's magnitude.

Contribution

It presents the first constraints on the chameleonic SZ effect in the Coma cluster by combining radial profile and frequency band measurements, estimating the coupling strength.

Findings

Measured the thermal SZ effect as -400±40 microKelvin.

Set an upper bound on the photon-scalar coupling g < (8.7 - 39.4) x 10^{-10} GeV^{-1}.

Provided the first observational constraints on the chameleonic SZ effect in galaxy clusters.

Abstract

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 centre of the Coma cluster in different frequency bands, to find Delta T_{SZ,RJ}(0)=-400+/-40 microKelvin and Delta T_{CSZ}^{204 GHz}(0)=-20+/-15 microKelvin (68% CL) for the thermal SZ and CSZ effects in the cluster respectively. The central value leads to an estimate of the photon to scalar (or pseudoscalar) coupling strength of g = (5.2 - 23.8) x 10^{-10} GeV^{-1}, while the 95% confidence bound is estimated to be g < (8.7 - 39.4) x 10^{-10} GeV^{-1}.