Estimating the heterogeneity of pressure profiles within a complete sample of 55 galaxy clusters: a Bayesian Hierarchical Model

Abstract

Galaxy clusters exhibit heterogeneity in their pressure profiles, even after rescaling, highlighting the need for adequately sized samples to accurately capture variations across the cluster population. We present a Bayesian hierarchical model that simultaneously fits individual cluster parameters and the underlying population distribution, providing estimates of the population-averaged pressure profile and the intrinsic scatter, as well as accurate pressure estimates for individual objects. We introduce a highly flexible, low-covariance, and interpretable parameterization of the pressure profile based on restricted cubic splines. We model the scatter properly accounting for outliers, and we incorporate corrections for beam and transfer function, as required for SZ data. Our model is applied to the largest non-stacked sample of individual cluster radial profiles, extracted from SPT+Planck Compton-y maps. This is a complete sample of 55 clusters, with $0.05<z<0.30$ and $M_{500}>4\times 10^{14}{M}_{\odot }$, enabling subdivision into sizable morphological classes based on eROSITA data. The shape of the population-averaged profile, at our 250 kpc FWHM resolution, closely resembles the universal pressure profile, despite the flexibility of our model to accommodate alternative shapes, with a ~12% lower normalization, similar to what is needed to alleviate the tension between cosmological parameters derived from the CMB and Planck SZ cluster counts. Beyond $r_{500}$, our profile is steeper than previous determinations. The intrinsic scatter is consistent with or lower than previous estimates, despite the broader diversity expected from our SZ selection. Our flexible pressure modelization identifies a few clusters with non-standard concavity in their radial profiles but no outliers in amplitude. When dividing the sample by morphology, we find remarkably similar pressure profiles across classes.

13 pages, 18 figures, accepted for publication in Astronomy and Astrophysics

References in corpus (15)

• Galaxy Clusters Discovered via the Sunyaev-Zel'dovich Effect in the 2500-square-degree SPT-SZ survey
• Euclid. I. Overview of the Euclid mission
• Systematics in the X-ray Cluster Mass Estimators
• The galaxy cluster mass scale and its impact on cosmological constraints from the cluster population
• XMM-Newton and Chandra Cross Calibration Using HIFLUGCS Galaxy Clusters: Systematic Temperature Differences and Cosmological Impact
• Shocks in the Stacked Sunyaev-Zel'dovich Profiles of Clusters II: Measurements from SPT-SZ + Planck Compton-y Map
• ComPRASS: a Combined Planck-RASS catalogue of X-ray-SZ clusters
• Pressure profiles of distant galaxy clusters in the Planck catalog
• Thermodynamic evolution of the $z=1.75$ galaxy cluster IDCS J1426.5+3508
• Witnessing the intracluster medium assembly at the cosmic noon in JKCS041
• The Evolution and Mass Dependence of Galaxy Cluster Pressure Profiles at 0.05 $\le z\le$ 0.60 and $4\times 10^{14}$ M${}_{\odot }$ $\le {\text{M}}_{500}\le 30\times 10^{14}$ M${}_{\odot }$
• Joint measurement of the galaxy cluster pressure profile with Planck and SPT-SZ
• The SRG/eROSITA all-sky survey: The morphologies of clusters of galaxies I: A catalogue of morphological parameters
• PreProFit -- Pressure Profile Fitter for galaxy clusters
• CHEX-MATE: pressure profiles of 6 galaxy clusters as seen by SPT and Planck