Tomographic measurement of the intergalactic gas pressure through galaxy-tSZ cross-correlations

TL;DR

This study uses galaxy-tSZ cross-correlations to measure the redshift evolution of intergalactic gas pressure and the hydrostatic mass bias, providing new constraints on gas thermodynamics and energy processes in galaxy clusters.

Contribution

It presents the first precise tomographic measurements of the gas pressure and mass bias evolution using full-sky surveys, improving constraints on cluster physics and cosmological parameters.

Findings

No evidence for redshift dependence of mass bias parameter.

Measured hydrostatic mass bias $1-b_{H} = 0.75 \\pm 0.03$ consistent with previous estimates.

Provided the most stringent constraints on the redshift evolution of gas pressure.

Abstract

We cross-correlate maps of the thermal Sunyaev-Zeldovich (tSZ) Compton-$y$ parameter published by Planck with the projected distribution of galaxies in a set of low-redshift tomographic bins. We use the nearly full-sky 2MASS Photometric Redshift and WISE $\times$ SuperCOSMOS public catalogues, covering the redshift range $z\lesssim0.4$. Our measurements allow us to place constraints on the redshift dependence of the mass-observable relation for tSZ cluster count analyses in terms of the so-called 'hydrostatic mass bias' parameter $1-b_{\rm H}$. These results can also be interpreted as measurements of the bias-weighted average gas pressure $\langle bP_e\rangle$ as a function of redshift, a quantity that can be related to the thermodynamics of gas inside haloes and used to constrain energy injection processes. We measure $1-b_{\rm H}$ with $\sim6\%$ precision in 6 equispaced redshift bins, and find no evidence for a redshift-dependent mass bias parameter, in agreement with previous analyses. Our mean value of $1-b_{\rm H} = 0.75\pm0.03$ is also in good agreement with the one estimated by the joint analysis of Planck cluster counts and CMB anisotropies calibrated with CMB lensing. Our measurements of $\langle bP_e\rangle$, at the level of $\sim10\%$ in each bin, are the most stringent constraints on the redshift dependence of this parameter to date, and agree well both with previous measurements and with theoretical expectations from shock-heating models.