LoCuSS: A Comparison of Sunyaev-Zel'dovich Effect and Gravitational Lensing Measurements of Galaxy Clusters

TL;DR

This study establishes a direct relationship between the Sunyaev-Zel'dovich effect signal and gravitational lensing mass measurements in galaxy clusters, revealing self-similar scaling and minimal hydrostatic bias in cluster cores.

Contribution

First to use gravitational lensing to measure cluster mass in SZ effect studies, providing new insights into cluster physics and mass-observable scaling relations.

Findings

Self-similar M_GL-Y scaling with 32% scatter

No hydrostatic mass bias detected in cluster cores

SZ effect less sensitive to core physics than X-ray observations

Abstract

We present the first measurement of the relationship between the Sunyaev-Zel'dovich effect signal and the mass of galaxy clusters that uses gravitational lensing to measure cluster mass, based on 14 X-ray luminous clusters at z~0.2 from the Local Cluster Substructure Survey. We measure the integrated Compton y-parameter, Y, and total projected mass of the clusters (M_GL) within a projected clustercentric radius of 350 kpc, corresponding to mean overdensities of 4000-8000 relative to the critical density. We find self-similar scaling between M_GL and Y, with a scatter in mass at fixed Y of 32%. This scatter exceeds that predicted from numerical cluster simulations, however, it is smaller than comparable measurements of the scatter in mass at fixed T_X. We also find no evidence of segregation in Y between disturbed and undisturbed clusters, as had been seen with T_X on the same physical scales. We compare our scaling relation to the Bonamente et al. relation based on mass measurements that assume hydrostatic equilibrium, finding no evidence for a hydrostatic mass bias in cluster cores (M_GL = 0.98+/-0.13 M_HSE), consistent with both predictions from numerical simulations and lensing/X-ray-based measurements of mass-observable scaling relations at larger radii. Overall our results suggest that the Sunyaev-Zel'dovich effect may be less sensitive than X-ray observations to the details of cluster physics in cluster cores.