Surface photometry of brightest cluster galaxies and intracluster stars in ΛCDM

• Published in: Monthly notices of the Royal Astronomical Society Vol. 451; no. 3; pp. 2703 - 2722
• Main Authors: Cooper, A. P., Gao, L., Guo, Q., Frenk, C. S., Jenkins, A., Springel, V., White, S. D. M.
• Format: Journal Article
• Language: English
• Published: Oxford University Press 11.08.2015
• Subjects: Clouds; Diffusion rate; Envelopes; Galactic clusters; Galaxies; Star clusters; Stars; Stellar mass; galaxies: elliptical and lenticular, cD; galaxies: structure; galaxies: clusters: general; methods: numerical; galaxies: photometry; galaxies: haloes
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stv1042

We simulate the phase-space distribution of stellar mass in nine massive Λ cold dark matter 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 × 1014 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 Mpc2 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.