Tracing the non-thermal pressure and hydrostatic bias in galaxy clusters

S. Ettori; D. Eckert

doi:10.1051/0004-6361/202142638

paper

Tracing the non-thermal pressure and hydrostatic bias in galaxy clusters

arXiv:2112.07554 · doi:10.1051/0004-6361/202142638

Abstract

We present a modelization of the non-thermal pressure, $P_{N T}$ , and we apply it to the X-ray (and Sunayev-Zel'dovich) derived radial profiles of the X-COP galaxy clusters. We relate the amount of non-thermal pressure support to the hydrostatic bias, $b$ , and speculate on how we can interpret this $P_{N T}$ in terms of the expected levels of turbulent velocity and magnetic fields. Current upper limits on the turbulent velocity in the intracluster plasma are used to build a distribution $N (< b) - b$ , from which we infer that 50 per cent of local galaxy clusters should have $b < 0.2$ ( $b < 0.33$ in 80 per cent of the population). The measured bias in the X-COP sample that includes relaxed massive nearby systems is 0.03 in 50% of the objects and 0.17 in 80% of them. All these values are below the amount of bias required to reconcile the observed cluster number count in the cosmological framework set from Planck.

arXiv comment6 pages, 3 figures. Accepted for publication in A&A Letters

Tracing the non-thermal pressure and hydrostatic bias in galaxy clusters

Abstract

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