2015MNRAS.451.2703C

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 (M200 ~ 7.5-33x10¹⁴M_☉). 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 percent of its total mass (the remainder is formed in situ). In circular BCG-centred apertures, the superposition of multiple debris clouds (each ≳ 10 percent 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 percent of stellar mass below a SB of µV ∼ 26.5mag/arcsec2 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 percent.