Resolving the hydrostatic mass profiles of galaxy clusters at z~1 with XMM-Newton and Chandra

TL;DR

This study uses XMM-Newton and Chandra data to measure the hydrostatic mass profiles of five massive galaxy clusters at z~1, testing structure formation models and comparing with simulations.

Contribution

It provides robust hydrostatic mass profiles at high redshift using combined X-ray methods and compares these with weak lensing and simulations, revealing potential evolution and biases.

Findings

X-ray masses are higher than weak lensing masses with a mean ratio of 1.39.

Results are consistent with expectations from numerical simulations.

Hints of evolution in cluster core properties or selection effects.

Abstract

We present a detailed study of the integrated total hydrostatic mass profiles of the five most massive ($M^{\mathrm{SZ}}_{500} > 5 \times 10^{14}$ M$_{\odot}$) galaxy clusters selected at $z\sim1$ via the Sunyaev-Zel'dovich effect. These objects represent an ideal laboratory to test structure formation models where the primary driver is gravity. Optimally exploiting spatially-resolved spectroscopic information from XMM-Newton and Chandra observations, we used both parametric (forward, backward) and non-parametric methods to recover the mass profiles, finding that the results are extremely robust when density and temperature measurements are both available. Our X-ray masses at $R_{500}$ are higher than the weak lensing masses obtained from the Hubble Space Telescope (HST), with a mean ratio of $1.39^{+0.47}_{-0.35}$. This offset goes in the opposite direction to that expected in a scenario where the hydrostatic method yields a biased, underestimated, mass. We investigated halo shape parameters such as sparsity and concentration, and compared to local X-ray selected clusters, finding hints for evolution in the central regions (or for selection effects). The total baryonic content is in agreement with the cosmic value at $R_{500}$. Comparison with numerical simulations shows that the mass distribution and concentration are in line with expectations. These results illustrate the power of X-ray observations to probe the statistical properties of the gas and total mass profiles in this high-mass, high-redshift regime.