Galaxy Kinematics and Mass Calibration in Massive SZE Selected Galaxy Clusters to z=1.3

TL;DR

This study uses galaxy kinematics in SZE-selected clusters up to z=1.3 to measure cluster masses, finding good agreement with some methods but a notable discrepancy with cosmological models at high redshift.

Contribution

It provides a detailed dynamical analysis of galaxy clusters using Jeans modeling, extending mass calibration to higher redshifts and comparing results with cosmological expectations.

Findings

Dynamical mass estimates agree with weak lensing and X-ray measurements.

Mass calibration shows a 2.2σ lower value than ΛCDM predictions with external priors.

Discrepancy between dynamical and cosmological masses increases with redshift.

Abstract

The galaxy phase-space distribution in galaxy clusters provides insights into the formation and evolution of cluster galaxies, and it can also be used to measure cluster mass profiles. We present a dynamical study based on $\sim$3000 passive, non-emission line cluster galaxies drawn from 110 galaxy clusters. The galaxy clusters were selected using the Sunyaev-Zel'dovich effect (SZE) in the 2500~deg$^2$ SPT-SZ survey and cover the redshift range $0.2 < z < 1.3$. We model the clusters using the Jeans equation, while adopting NFW mass profiles and a broad range of velocity dispersion anisotropy profiles. The data prefer velocity dispersion anisotropy profiles that are approximately isotropic near the center and increasingly radial toward the cluster virial radius, and this is true for all redshifts and masses we study. The pseudo-phase-space density profile of the passive galaxies is consistent with expectations for dark matter particles and subhalos from cosmological $N$-body simulations. The dynamical mass constraints are in good agreement with external mass estimates of the SPT cluster sample from either weak lensing, velocity dispersions, or X-ray $Y_X$ measurements. However, the dynamical masses are lower (at the 2.2$\sigma$ level) when compared to the mass calibration favored when fitting the SPT cluster data to a $\Lambda$CDM model with external cosmological priors, including CMB anisotropy data from Planck. The discrepancy grows with redshift, where in the highest redshift bin the ratio of dynamical to SPT+Planck masses is $\eta=0.63^{+0.13}_{-0.08}\pm0.06$ (statistical and systematic), corresponding to a $2.6\sigma$ discrepancy.