2016/06/07 by Veronica Biffi, V. Biffi, S. Borgani +14
Mathematics · Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics #Cluster (spacecraft) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Hydrostatic equilibrium #Mathematics #Physics #Quantum mechanics #RADIUS #Standard deviation #Statistical physics #Statistics #Stellar, planetary, and galactic studies #Virial theorem #astro-ph.CO
paper · pdf · doi:10.3847/0004-637x/827/2/112
14 pages, 13 figures, 1 table; submitted
arxiv created 2016/06/07 · openalex publication_date 2016/08/12 · arxiv updated 2016/08/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
ABSTRACT In this paper, we investigate the level of hydrostatic equilibrium (HE) in the intracluster medium of simulated galaxy clusters, extracted from state-of-the-art cosmological hydrodynamical simulations performed with the Smoothed-Particle-Hydrodynamic code GADGET-3. These simulations include several physical processes, among which are stellar and active galactic nucleus feedback, and have been performed with an improved version of the code that allows for a better description of hydrodynamical instabilities and gas mixing processes. Evaluating the radial balance between the gravitational and hydrodynamical forces via the gas accelerations generated, we effectively examine the level of HE in every object of the sample and its dependence on the radial distance from the center and on the classification of the cluster in terms of either cool-coreness or dynamical state. We find an average deviation of 10%–20% out to the virial radius, with no evident distinction between cool-core and non-cool-core clusters. Instead, we observe a clear separation between regular and disturbed systems, with a more significant deviation from HE for the disturbed objects. The investigation of the bias between the hydrostatic estimate and the total gravitating mass indicates that, on average, this traces the deviation from HE very well, even though individual cases show a more complex picture. Typically, in the radial ranges where mass bias and deviation from HE are substantially different, the gas is characterized by a significant amount of random motions ( ), relative to thermal ones. As a general result, the HE-deviation and mass bias, at a given distance from the cluster center, are not very sensitive to the temperature inhomogeneities in the gas.