Surface photometry of brightest cluster galaxies and intracluster stars in ΛCDM

Abstract

We simulate the phase-space distribution of stellar mass in nine massive ΛCDM galaxy clusters by applying the semi-analytic particle tagging method of Cooper et al. to the Phoenix suite of high-resolution N -body simulations (M 200 ≈ 7.5-33 × 10 14 M ). The resulting surface brightness (SB) profiles of brightest cluster galaxies (BCGs) match well to observations. On average, stars formed in galaxies accreted by the BCG account for 90 per cent of its total mass (the remainder is formed in situ). In circular BCG-centred apertures, the superposition of multiple debris clouds (each 10 per cent of the total BCG mass) from different progenitors can result in an extensive outer diffuse component, qualitatively similar to a 'cD envelope'. These clouds typically originate from tidal stripping at z 1 and comprise both streams and the extended envelopes of other massive galaxies in the cluster. Stars at very low SB contribute a significant fraction of the total cluster stellar mass budget: in the central 1 Mpc 2 of a z ∼ 0.15 cluster imaged at SDSS-like resolution, our fiducial model predicts 80-95 per cent of stellar mass below a SB of µ V ∼ 26.5 mag arcsec −2 is associated with accreted stars in the envelope of the BCG. The ratio of BCG stellar mass (including this diffuse component) to total cluster stellar mass is ∼ 30 per cent.

The outer regions of the giant Virgo galaxy M 87 Kinematic separation of stellar halo and intracluster light

“…They suggested that their blue GCs at distances >215 kpc are part of the intracluster component of Virgo. Cosmological simulations Cui et al 2014;Cooper et al 2015) predict that the density of this component would then increase inwards. Durrell et al (2014) also found evidence for a spatial asymmetry of GCs surrounding M 87 for major axis distances larger than 20 , with an excess of tracers in the NW region (mostly the blue population).…”

“…Using a particle tagging method to analyse galaxy clusters in ΛCDM simulations, Cooper et al (2015) consider the BCG and ICL as a single entity consisting of all stars, which are not bound to any cluster subhalos. They then split the BCG stars into accreted stars and in situ stars, and find that the large majority of BCG stars are accreted stars.…”

“…On the other hand, tidal forces strip stars from satellite galaxies which end up orbiting the cluster as unbound ICL (Gnedin 2003;Murante et al 2004Murante et al , 2007Mihos 2004;Rudick et al 2006). In the ICL and the outer regions of BCGs where the dynamical timescales are long, fossil records of accretion events can be preserved over extended periods (Willman et al 2004;Rudick et al 2009;Cooper et al 2015). Hence, the study of the luminosity, distribution, and kinematics of galaxy halos and ICL A&A 579, A135 (2015) may provide information on the evolution of galaxies and their host clusters.…”

“…Other studies do not adopt this kind of dynamical definition of the two components and treat the BCG and ICL as a single system at the centre of the cluster, consisting of all stars that are not bound to any satellite subhalos in the cluster (e.g. Murante et al 2004;Cooper et al 2015).…”

THE FORNAX DEEP SURVEY WITH VST. I. THE EXTENDED AND DIFFUSE STELLAR HALO OF NGC 1399 OUT TO 192 kpc

“…Recent studies have demonstrated that the overall structure of stellar halos, their stellar populations, and the properties of their dynamical substructures directly probe two fundamental aspects of galaxy formation in the ΛCDM (cold dark matter) model: the hierarchical assembly of massive galaxies and their dark matter halos and the balance between in situ star formation and the accretion of stars through mergers (Cooper et al 2013(Cooper et al , 2015a(Cooper et al , 2015bPillepich et al 2015).…”