# GALAXIES IN X-RAY SELECTED CLUSTERS AND GROUPS IN DARK ENERGY SURVEY DATA. I. STELLAR MASS GROWTH OF BRIGHT CENTRAL GALAXIES SINCE z similar to 1.2

Zhang, Y and Miller, C and McKay, T and Rooney, P and Evrard, AE and Romer, AK and Perfecto, R and Song, J and Desai, S and Mohr, J and Wilcox, H and Bermeo-Hernandez, A and Jeltema, T and Hollowood, D and Bacon, D and Capozzi, D and Collins, CA and Das, R and Gerdes, D and Hennig, C and Hilton, M and Hoyle, B and Kay, S and Liddle, A and Mann, RG and Mehrtens, N and Nichol, RC and Papovich, C and Sahlen, M and Soares-Santos, M and Stott, J and Viana, PT and Abbott, T and Abdalla, FB and Banerji, M and Bauer, AH and Benoit-Levy, A and Bertin, E and Brooks, D and Buckley-Geer, E and Burke, DL and Rosell, AC and Castander, FJ and Diehl, HT and Doel, P and Cunha, CE and Eifler, TF and Fausti Neto, A and Fernandez, E and Flaugher, B and Fosalba, P and Frieman, J and Gaztanaga, E and Gruen, D and Gruendl, RA and Honscheid, K and James, D and Kuehn, K and Kuropatkin, N and Lahav, O and Maia, MAG and Makler, M and Marshall, JL and Martini, P and Miquel, R and Ogando, R and Plazas, AA and Roodman, A and Rykoff, ES and Sako, M and Sanchez, E and Scarpine, V and Schubnell, M and Sevilla, I and Smith, RC and Sobreira, F and Suchyta, E and Swanson, MEC and Tarle, G and Thaler, J and Tucker, D and Vikram, V and da Costa, LN (2016) GALAXIES IN X-RAY SELECTED CLUSTERS AND GROUPS IN DARK ENERGY SURVEY DATA. I. STELLAR MASS GROWTH OF BRIGHT CENTRAL GALAXIES SINCE z similar to 1.2. ASTROPHYSICAL JOURNAL, 816 (2). ISSN 0004-637X

Using the science verification data of the Dark Energy Survey for a new sample of 106 X-ray selected clusters and groups, we study the stellar mass growth of bright central galaxies (BCGs) since redshift z ~ 1.2. Compared with the expectation in a semi-analytical model applied to the Millennium Simulation, the observed BCGs become under-massive/under-luminous with decreasing redshift. We incorporate the uncertainties associated with cluster mass, redshift, and BCG stellar mass measurements into an analysis of a redshift-dependent BCG-cluster mass relation, ${m}_{*}\propto {\left(\frac{{M}_{200}}{1.5\times {10}^{14}{M}_{\odot }}\right)}^{0.24\pm 0.08}{(1+z)}^{-0.19\pm 0.34}$, and compare the observed relation to the model prediction. We estimate the average growth rate since z = 1.0 for BCGs hosted by clusters of M200,z = 1013.8 M⊙; at z = 1.0: m*,BCG appears to have grown by 0.13 ± 0.11 dex, in tension at the ~2.5σ significance level with the 0.40 dex growth rate expected from the semi-analytic model. We show that the build-up of extended intracluster light after z = 1.0 may alleviate this tension in BCG growth rates.