Abstract
Recent hydrodynamic cosmological simulations cover volumes up to Gpc^3 and resolve halos across a wide range of masses and environments, from massive galaxy clusters down to normal galaxies, while following a large variety of physical processes (star formation, chemical enrichment, AGN feedback) to allow a self-consistent comparison to observations at multiple wavelengths. Using the Magneticum simulations, we investigate the buildup of the diffuse stellar component (DSC) around massive galaxies within group and cluster environments. The DSC in our simulations reproduces the spatial distribution of the observed intracluster light (ICL) as well as its kinematic properties remarkably well. For galaxy clusters and groups we find that, although the DSC in almost all cases shows a clear separation from the brightest cluster galaxy (BCG) with regard to its dynamic state, the radial stellar density distribution in many halos is often characterized by a single Sersic profile, representing both the BCG component and the DSC, very much in agreement with current observational results. Interestingly, even in those halos that clearly show two components in both the dynamics and the spatial distribution of the stellar component, no correlation between them is evident.
Highlights
Brightest cluster galaxies (BCGs), residing in the centers of galaxy clusters, are the most massive and luminous galaxies in the universe
We presented a detailed and statistically sound analysis of the stellar velocity distributions and the projected stellar radial surface density profiles of galaxy clusters and galaxy groups selected from the Magneticum pathfinder simulation sample
Using two volumes of different sizes and resolutions, we showed that for more than 90% of all 928 clusters and groups in our sample the velocity distributions are represented best by a superposition of two Maxwellian distributions, with the slower component representing the BCG of the cluster and the faster component representing the diffuse stellar component (DSC)
Summary
Brightest cluster galaxies (BCGs), residing in the centers of galaxy clusters, are the most massive and luminous galaxies in the universe During their lifetime, they experience frequent interactions with satellite galaxies, and their growth is dominated by merger events. While the velocity dispersion of the stars in the BCG represents the central mass of the stars, the velocity dispersion of the DSC is much larger and is comparable to that of the dark matter halo (see, for example, Dolag et al, 2010 [2], Bender et al, 2015 [3], and Longobardi et al, 2015 [4]) More details on this matter can be found in a recent review by Mihos et al, 2016 [5]. In this study we analyse the velocity distributions as well as the projected radial surface density profiles of the stellar component in galaxy clusters selected from a state-of-the-art cosmological simulation, and test for possible correlations between these distributions
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