LoCuSS: Hydrostatic Mass Measurements of the High-$L_X$ Cluster Sample -- Cross-calibration of Chandra and XMM-Newton

TL;DR

This study performs a cross-calibration of Chandra and XMM-Newton X-ray observations of galaxy clusters, confirming consistent mass measurements and analyzing the impact of non-thermal pressure support and Sunyaev-Zel'dovich effect scaling relations.

Contribution

It introduces a consistent analysis method for both satellites and verifies the cross-calibration of mass measurements, including background modeling and comparison with weak-lensing data.

Findings

Chandra and XMM-Newton mass measurements are consistent within a few percent.

Non-thermal pressure support at $r_{500}$ is approximately 7%.

Mass scatter at fixed $Y_{sph}$ is about 16%, aligning with theoretical expectations.

Abstract

We present a consistent analysis of Chandra and XMM-Newton observations of an approximately mass-selected sample of 50 galaxy clusters at $0.15<z<0.3$ -- the "LoCuSS High-$L_X$ Sample". We apply the same analysis methods to data from both satellites, including newly developed analytic background models that predict the spatial variation of the Chandra and XMM-Newton backgrounds to $<2\%$ and $<5\%$ precision respectively. To verify the cross-calibration of Chandra and XMM-Newton-based cluster mass measurements, we derive the mass profiles of the 21 clusters that have been observed with both satellites, extracting surface brightness and temperature profiles from identical regions of the respective datasets. We obtain consistent results for the gas and total hydrostatic cluster masses: the average ratio of Chandra- to XMM-Newton-based measurements of $M_{\rm gas}$ and $M_X$ at $r_{500}$ are $0.99\pm0.02$ and $1.02\pm0.05$, respectively with an intrinsic scatter of $\sim3\%$ for gas masses and $\sim8\%$ for hydrostatic masses. Comparison of our hydrostatic mass measurements at $r_{500}$ with the latest LoCuSS weak-lensing results indicate that the data are consistent with non-thermal pressure support at this radius of $\sim7\%$. We also investigate the scaling relation between our hydrostatic cluster masses and published integrated Compton parameter $Y_{sph}$ measurements from the Sunyaev-Zel'dovich Array. We measure a scatter in mass at fixed $Y_{sph}$ of $\sim16\%$ at $\Delta=500$, which is consistent with theoretical predictions of $\sim10-15\%$ scatter.