The pressure profiles of hot gas in local galaxy groups

TL;DR

This paper investigates the thermal pressure profiles of local galaxy groups to better understand baryon physics and improve models predicting the Sunyaev-Zel'dovich power spectrum, which is crucial for cosmological constraints.

Contribution

It provides observational evidence that the pressure profiles of galaxy groups align with those of larger clusters, aiding in refining SZ effect models.

Findings

Group pressure profiles agree with universal cluster profiles.

The Y_{sph, 500} - M_500 relation matches cluster relations.

Discussion of methods to resolve SZ power spectrum discrepancies.

Abstract

Recent measurements of the Sunyaev-Zel'dovich (SZ) angular power spectrum from the South Pole Telescope (SPT) and the Atacama Cosmology Telescope (ACT) demonstrate the importance of understanding baryon physics when using the SZ power spectrum to constrain cosmology. This is challenging since roughly half of the SZ power at l=3000 is from low-mass systems with 10^13 h^-1 M_sun < M_500 < 1.5x10^14 h^-1 M_sun, which are more difficult to study than systems of higher mass. We present a study of the thermal pressure content for a sample of local galaxy groups from Sun et al. (2009). The group Y_{sph, 500} - M_500 relation agrees with the one for clusters derived by Arnaud et al. (2010). The group median pressure profile also agrees with the universal pressure profile for clusters derived by Arnaud et al. (2010). With this in mind, we briefly discuss several ways to alleviate the tension between the measured low SZ power and the predictions from SZ templates.