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

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 $z\lesssim 0.4$. 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 $1-b_{\mathrm{H}}$. These results can also be interpreted as measurements of the bias-weighted average gas pressure $⟨b{P}_e⟩$ 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 $1-b_{\mathrm{H}}$ with $\sim 6\%$ 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 $1-b_{\mathrm{H}}=0.75\pm 0.03$ 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 $⟨b{P}_e⟩$, at the level of $\sim 10\%$ 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.

19 pages, 10 figures. Published in MNRAS. Analysis pipeline available at https://github.com/nikfilippas/yxg