Detection of thermal Sunyaev-Zel'dovich Effect in the circumgalactic medium of low-mass galaxies -- a surprising pattern in self-similarity and baryon sufficiency

TL;DR

This study measures the thermal Sunyaev-Zel'dovich effect in the circumgalactic medium of low-mass galaxies, revealing unexpected patterns in self-similarity and baryon content, and extends previous analyses to lower mass ranges.

Contribution

It introduces improved data analysis and modeling techniques to detect the tSZ effect in lower-mass galaxies and uncovers a non-monotonic baryon fraction trend with galaxy mass.

Findings

Steeper than expected M_{500}-Y relation in low-mass galaxies.

Baryon fraction peaks at intermediate stellar masses.

Detection of tSZ signal in galaxies with M_\,star\,= 10^{10.6-11.3} M_\,sun\,.

Abstract

We report on the measurement of the thermal Sunyaev-Zel'dovich (tSZ) Effect in the circumgalactic medium (CGM) of 641,923 galaxies with $\rm M_\star$=$\rm 10^{9.8-11.3}M_\odot$ at $z<$0.5, pushing the exploration of tSZ Effect to lower-mass galaxies compared to previous studies. We cross-correlate the galaxy catalog of $WISE$ and $SuperCosmos$ with the Compton-$y$ maps derived from the combined data of $Atacama$ $Cosmology$ $Telescope$ and $Planck$. We improve on the data analysis methods (correcting for cosmic infrared background and Galactic dust, masking galaxy clusters and radio sources, stacking, aperture photometry), as well as modeling (taking into account beam smearing, "two-halo" term, zero-point offset). We have constrained the thermal pressure in the CGM of $\rm M_\star$=$\rm 10^{10.6-11.3}M_\odot$ galaxies for a generalized NFW profile and provided upper limits for $\rm M_\star$=$\rm 10^{9.8-10.6}M_\odot$ galaxies. The relation between $\rm M_{500}$ (obtained from an empirical $\rm M_\star$-$\rm M_{200}$ relation and a concentration factor) and $\rm \tilde Y^{sph}_{R500}$ (a measure of the thermal energy within R$_{500}$) is $>$2$\sigma$ steeper than the self-similarity and the deviation from the same that has been reported previously in higher mass halos. We calculate the baryon fraction of the galaxies, $f_b$, assuming the CGM to be at the virial temperature that is derived from $\rm M_{200}$. $f_b$ exhibits a non-monotonic trend with mass, with $\rm M_\star$=$\rm 10^{10.9-11.2}M_\odot$ galaxies being baryon sufficient.