Shocks in the stacked Sunyaev-Zel'dovich profiles of clusters II: Measurements from SPT-SZ plus Planck Compton-y map

We search for the signature of cosmological shocks in stacked gas pressure profiles of galaxy clusters using data from the South Pole Telescope (SPT). Specifically, we stack the latest Compton-y maps from the 2500 deg(2) SPT-SZ survey on the locations of clusters identified in that same data set. The sample contains 516 clusters with mean mass < M-200m > = 10(14.9) M-circle dot and redshift < z > = 0.55. We analyse in parallel a set of zoom-in hydrodynamical simulations from THE THREE HUNDRED project. The SPT-SZ data show two features: (i) a pressure deficit at R/R-200m = 1.08 +/- 0.09, measured at 3.1 sigma significance and not observed in the simulations, and; (ii) a sharp decrease in pressure at R/R-200m = 4.58 +/- 1.24 at 2.0 sigma significance. The pressure deficit is qualitatively consistent with a shock-induced thermal non-equilibrium between electrons and ions, and the second feature is consistent with accretion shocks seen in previous studies. We split the cluster sample by redshift and mass, and find both features exist in all cases. There are also no significant differences in features along and across the cluster major axis, whose orientation roughly points towards filamentary structure. As a consistency test, we also analyse clusters from the Planck and Atacama Cosmology 'telescope Polarimeter surveys and find quantitatively similar features in the pressure profiles. Finally, we compare the accretion shock radius (R-sh,R- acc) with existing measurements of the splashback radius (R-sp) for SPT-SZ and constrain the lower limit of the ratio, R-sh,R- acc/R-sp > 2.16 +/- 0.59.

Automated summary

In this study, we searched for the signature of cosmological shocks in the stacked gas pressure profiles of galaxy clusters. The analysis of data from the South Pole Telescope revealed two features: a pressure deficit and a sharp decrease in pressure, both consistent with shock-induced thermal non-equilibrium and accretion shocks. These features were observed in all cases, regardless of redshift and mass, and exhibited no significant differences along and across the cluster major axis.