CLUMP-3D: the lack of non-thermal motions in galaxy cluster cores

Abstract

We report the non-thermal pressure fraction (P_(nt)/P_(tot)) obtained from a three-dimensional triaxial analysis of 16 galaxy clusters in the CLASH sample using gravitational lensing (GL) data primarily from Subaru and HST, X-ray spectroscopic imaging from Chandra, and Sunyaev–Zel'dovich effect (SZE) data from Planck and Bolocam. Our results span the approximate radial range 0.015–0.4 R_(200m) (∼35–1000 kpc). At cluster-centric radii smaller than 0.1 R_(200m) the ensemble average P_(nt)/P_(tot) is consistent with zero with an upper limit of 9 per cent, indicating that heating from active galactic nuclei and other relevant processes does not produce significant deviations from hydrostatic equilibrium (HSE). The ensemble average P_(nt)/P_(tot) increases outside of this radius to approximately 20 per cent at 0.4 R_(200m), as expected from simulations, due to newly accreted material thermalizing via a series of shocks. Also in agreement with simulations, we find significant cluster-to-cluster variation in P_(nt)/P_(tot) and little difference in the ensemble average P_(nt)/P_(tot) based on dynamical state. We conclude that on average, even for diverse samples, HSE-derived masses in the very central regions of galaxy clusters require only modest corrections due to non-thermal motions.

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