Velocity dispersion of brightest cluster galaxies in cosmological simulations

MARINI, I; BORGANI, S; SARO, A; GRANATO, G L; RAGONE-FIGUEROA, C; SARTORIS, B; DOLAG, K; MURANTE, G; RAGAGNIN, A; WANG, Y

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2021 vol. 507 p. 5780 - 5795

0035-8711

Using the DIANOGA hydrodynamical zoom-in simulation set of galaxy clusters, we analyse the dynamics traced by starsbelonging to the brightest cluster galaxies (BCGs) and their surrounding diffuse component, forming the intracluster light (ICL),and compare it to the dynamics traced by dark matter and galaxies identified in the simulations. We compute scaling relations?σ BCG, M 200 ?σ 200 , M BCG?M 200 ,between the BCG and cluster velocity dispersions and their corresponding masses (i.e. M BCGand σ BCG ?σ 200 ), we find in general a good agreement with observational results. Our simulations also predict σ BCG ?σ 200 relationto not change significantly up to redshift z = 1, in line with a relatively slow accretion of the BCG stellar mass at late times. Weanalyse the main features of the velocity dispersion profiles, as traced by stars, dark matter, and galaxies. As a result, we discussthat observed stellar velocity dispersion profiles in the inner cluster regions are in excellent agreement with simulations. Wealso report that the slopes of the BCG velocity dispersion profile from simulations agree with what is measured in observations,confirming the existence of a robust correlation between the stellar velocity dispersion slope and the cluster velocity dispersion(thus, cluster mass) when the former is computed within 0.1R 500 . Our results demonstrate that simulations can correctly describethe dynamics of BCGs and their surrounding stellar envelope, as determined by the past star formation and assembly historiesof the most massive galaxies of the Universe.