Measurement of the $T_{\mathrm{CMB}}$ evolution from the Sunyaev-Zel'dovich effect

Abstract

In the standard hot cosmological model, the black-body temperature of the Cosmic Microwave Background (CMB), $T_{\mathrm{CMB}}$, increases linearly with redshift. Across the line of sight CMB photons interact with the hot ($\sim 10^{7-8}$ K) and diffuse gas of electrons from galaxy clusters. This interaction leads to the well known thermal Sunyaev-Zel'dovich effect (tSZ), which produces a distortion of the black-body emission law, depending on $T_{\mathrm{CMB}}$. Using tSZ data from the $Planck$ satellite it is possible to constrain $T_{\mathrm{CMB}}$ below z=1. Focusing on the redshift dependance of $T_{\mathrm{CMB}}$ we obtain $T_{\mathrm{CMB}}(z)=(2.726\pm 0.001)\times (1+z{)}^{1-{\hat{I}}^2}$ K with ${\hat{I}}^2=0.009\pm 0.017$, improving previous constraints. Combined with measurements of molecular species absorptions, we derive ${\hat{I}}^2=0.006\pm 0.013$. These constraints are consistent with the standard (i.e. adiabatic, ${\hat{I}}^2=0$) Big-Bang model.

13 pages, 8 figures, A&A in press