The XMM Cluster Outskirts Project (X-COP): Thermodynamic properties of the Intracluster Medium out to $R_{200}$ in Abell 2319

TL;DR

This study combines X-ray and SZ data to analyze the thermodynamic properties of galaxy cluster Abell 2319 out to its virial radius, revealing effects of ongoing mergers and non-thermal pressure support.

Contribution

It provides high-precision measurements of the cluster's mass and thermodynamic profiles, and demonstrates the impact of mergers on intracluster medium properties using azimuthal sector analysis.

Findings

Mass within R200 is accurately measured as 9.76 ± 0.16(stat.) ± 0.31(syst.) × 10^14 M_sun.

Merger activity injects non-thermal pressure, accounting for about 40% of total pressure at R200.

Clumpiness of density is below 20%, mainly due to large-scale inhomogeneities from mergers.

Abstract

We present the joint analysis of the X-ray and SZ signals in A2319, the galaxy cluster with the highest signal-to-noise ratio in Planck maps and that has been surveyed within our XMM Cluster Outskirts Project (X-COP). We recover the thermodynamical profiles by the geometrical deprojection of the X-ray surface brightness, of the SZ comptonization parameter, and an accurate and robust spectroscopic measurements of the temperature. We resolve the clumpiness of the density to be below 20 per cent demonstrating that most of this clumpiness originates from the ongoing merger and can be associated to large-scale inhomogeneities. This analysis is done in azimuthally averaged radial bins and in eight independent angular sectors, enabling us to study in details the azimuthal variance of the recovered properties. Given the exquisite quality of the X-ray and SZ datasets, we constrain at $R_{200}$ the total hydrostatic mass, modelled with a NFW profile, with very high precision ($M_{200} = 9.76 \pm 0.16^{stat.} \pm 0.31^{syst.} \times 10^{14} M_\odot$). We identify the ongoing merger and how it is affecting differently the gas properties in the resolved azimuthal sectors. We have several indications that the merger has injected a high level of non-thermal pressure in this system: the clumping free density profile is above the average profile obtained by stacking Rosat observations; the gas mass fraction exceeds the expected cosmic gas fraction beyond $R_{500}$; the pressure profile is flatter than the fit obtained by the Planck collaboration; the entropy profile is flatter than the mean one predicted from non-radiative simulations; the analysis in azimuthal sectors has revealed that these deviations occur in a preferred region of the cluster. All these tensions are resolved by requiring a relative support of about 40 per cent from non-thermal to the total pressure at $R_{200}$.