Shocks in the Stacked Sunyaev-Zel'dovich Profiles of Clusters II: Measurements from SPT-SZ + Planck Compton-y Map

Abstract

We search for the signature of shocks in stacked gas pressure profiles of galaxy clusters using data from the South Pole Telescope (SPT). Specifically, we stack the recently released Compton-𝑦 maps from the 2500 deg 2 SPT-SZ survey on the locations of clusters identified in that same dataset. The sample contains 516 clusters with mean mass 𝑀 200m = 10 14.9 M and redshift 𝑧 = 0.55. We analyze in parallel a set of zoom-in hydrodynamical simulations from T T H project. The SPT-SZ data show two features: (i) a pressure deficit at 𝑅/𝑅 200m = 1.08 ± 0.09, measured at 3.1𝜎 significance and not observed in the simulations, and; (ii) a sharp decrease in pressure at 𝑅/𝑅 200m = 4.58 ± 1.24 at 2.0𝜎 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 analyze 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, acc ) with existing measurements of the splashback radius (𝑅 sp ) for SPT-SZ and constrain the lower limit of the ratio, 𝑅 sh, acc /𝑅 sp > 2.16 ± 0.59.

Correlations of Dark Matter, Gas and Stellar Profiles in Dark Matter Halos

“…The outskirts of the mean dark matter and gas density profiles in massive halos have received significant attention in recent times from both theory and observations (Walker et al 2019, and references therein), and can serve as probes of astrophysics and of cosmological structure formation (e.g., Aung et al 2021;Anbajagane et al 2021, for recent works). In the bottom panels of Figure 2, we see that in the cluster core the dark matter density profile has the least scatter of the three profiles, by about a factor of 2 or more.…”

ELUCID VII: Using Constrained Hydro Simulations to Explore the Gas Component of the Cosmic Web

“…As one can see, the simulated profile matches the observed one well at θ < 50 arcmins, corresponding to about 0.7 times the virial radius, but is lower around the virial radius. Recently, Anbajagane et al (2021) analyzed the SZ data of several hundred clusters and compared the results with simulations (Cui et al 2018). They found that the average profile of the simulated clusters is also lower than the observation outside the virial radius.…”

The Three Hundred: Cluster Dynamical States and Relaxation Time Scale

“…A more detailed introduction of The Three Hundred can be found in Cui et al (2018). Besides these studies on the cluster dynamical state which has been mentioned in the introduction, these simulated galaxy clusters have been used for different proposes: the filaments around the clusters (Rost et al 2021;Kuchner et al 2020Kuchner et al , 2021Kotecha et al 2021); the backsplash galaxies (Haggar et al 2020;Knebe et al 2020) and shock radius (Baxter et al 2021;Anbajagane et al 2021b). The advanced baryon models in hydrodynamic simulations allow us to perform a detailed investigation on the cluster properties, such as profiles (Mostoghiu et al 2019;Li et al 2020), substructure and its baryonic content (Arthur et al 2019;Haggar et al 2021;Mostoghiu et al 2021b,a), the cluster (non-)thermalization (Sayers et al 2021;Sereno et al 2021), the fundamental plane (Díaz-García et al 2021), and the cluster mass bias (Ansarifard et al 2020;Li et al 2021;Anbajagane et al 2021a).…”