Thermal Sunyaev-Zel'dovich Effect in the circumgalactic medium - III: does richness matter?

Abstract: We measure the thermal Sunyaev-Zel'dovich Effect in the circumgalactic/intragroup medium (CGM/IGrM) of 7 million $\rm M_{200c} = 10<sup>{12-14}$M$_\odot$ $z \leqslant 1$ DESI Legacy Survey galaxies/groups using ACT+Planck observations, and investigate for the first time how the thermal pressure depends on richness. We detect the one-halo term down to 10$<sup>{12.2}$M$_\odot$ at $5.8σ$. While several mass-richness bins are well described by the standard GNFW thermal-pressure profile ($β=5.49,r_o=0$), others favor a flatter and/or miscentered profile ($β=1.3-4.0,r_o&gt;0.1 \rm R_{200c}$), with the mass dependence of this pattern varying with richness. The wide variety of thermal pressure profiles across mass and richness indicates a range of physical regimes, from dominant thermal feedback to efficient cooling with subdominant thermal feedback, and even substantial cooling. In some mass bins, the super-virial ($\approx2-7 \rm T_{200c}$) temperature floor (the lowest temperature allowed by the data for baryon-sufficient halos) points to significant heating. However, dominant kinetic-mode feedback is not essential anywhere, challenging a universal (ejective)feedback-vs-gravity picture. The slope of the thermal energy-mass relation in IGrM is consistent with self-similarity, but in the CGM it falls below self-similarity by $7.3σ$. This makes halos of relatively low mass and richness the dominant contributors to the universe's thermal energy budget at $z\leqslant1$. We therefore argue that calibrations of thermal energy scaling relations must move beyond the convention of using mass as the sole demarcator and instead incorporate additional intrinsic and environmental properties of galaxies.