Nonthermal Pressure in the Outskirts of Abell 2142

TL;DR

This study analyzes X-ray data of galaxy cluster Abell 2142 to reveal that nonthermal pressure and gas clumping significantly influence the thermodynamics of its outskirts, aligning observations with theoretical expectations.

Contribution

It demonstrates the necessity of including nonthermal pressure components and gas clumping corrections to accurately model cluster outskirts using X-ray and SZ data.

Findings

Nonthermal pressure accounts for about 30% of total pressure at the virial radius.

Gas fraction becomes consistent with universal values when nonthermal pressure is considered.

Traditional methods using SZ and X-ray data may overlook nonthermal pressure support.

Abstract

Clumping and turbulence are expected to affect the matter accreted onto the outskirts of galaxy clusters. To determine their impact on the thermodynamic properties of Abell 2142 we perform an analysis of the X-ray temperature data from XMM-Newton via our SuperModel, a state-of-the-art tool for investigating the astrophysics of the intracluster medium already tested on many individual clusters (since Cavaliere et al. 2009). Using the gas density profile corrected for clumpiness derived by Tchernin et al. (2016), we find evidence for the presence of a nonthermal pressure component required to sustain gravity in the cluster outskirts of Abell 2142, that amounts to about 30% of the total pressure at the virial radius. The presence of the nonthermal component implies the gas fraction to be consistent with the universal value at the virial radius and the electron thermal pressure profile to be in good agreement with that inferred from the SZ data. Our results indicate that the presence of gas clumping and of a nonthermal pressure component are both necessary to recover the observed physical properties in the cluster outskirts. Moreover, we stress that an alternative method often exploited in the literature (included Abell 2142) to determine the temperature profile k_BT = P_e/n_e basing on a combination of the Sunyaev-Zel'dovich (SZ) pressure P_e and of the X-ray electron density n_e does not allow to highlight the presence of nonthermal pressure support in the cluster outskirts.