The influence of magnetic fields on the Sunyaev–Zel’dovich effect in clusters of galaxies

Abstract

We study the influence of intracluster large scale magnetic fields on the thermal Sunyaev–Zel’dovich (SZ) effect. In a macroscopic approach we complete the hydrostatic equilibrium equation with the magnetic field pressure component. Comparing the resulting mass distribution with a standard one, we derive a new electron density profile. For a spherically symmetric cluster model, this new profile can be written as the product of a standard ( β-) profile and a radius dependent function, close to unity, which takes into account the magnetic field strength. For non-cooling flow clusters we find that the observed magnetic field values can reduce the SZ signal by ∼10% with respect to the value estimated from X-ray observations and the β-model. If a cluster harbours a cooling flow, magnetic fields tend to weaken the cooling flow influence on the SZ-effect.