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Published July 21, 2014 | Published + Supplemental Material
Journal Article Open

The violent youth of bright and massive cluster galaxies and their maturation over 7 billion years


In this study, we investigate the formation and evolution mechanisms of the brightest cluster galaxies (BCGs) over cosmic time. At high redshift (z ∼ 0.9), we selected BCGs and most massive cluster galaxies (MMCGs) from the Cl1604 supercluster and compared them to low-redshift (z ∼ 0.1) counterparts drawn from the MCXC meta-catalogue, supplemented by Sloan Digital Sky Survey imaging and spectroscopy. We observed striking differences in the morphological, colour, spectral, and stellar mass properties of the BCGs/MMCGs in the two samples. High-redshift BCGs/MMCGs were, in many cases, star-forming, late-type galaxies, with blue broad-band colours, properties largely absent amongst the low-redshift BCGs/MMCGs. The stellar mass of BCGs was found to increase by an average factor of 2.51 ± 0.71 from z ∼ 0.9 to z ∼ 0.1. Through this and other comparisons, we conclude that a combination of major merging (mainly wet or mixed) and in situ star formation are the main mechanisms which build stellar mass in BCGs/MMCGs. The stellar mass growth of the BCGs/MMCGs also appears to grow in lockstep with both the stellar baryonic and total mass of the cluster. Additionally, BCGs/MMCGs were found to grow in size, on average, a factor of ∼3, while their average Sérsic index increased by ∼0.45 from z ∼ 0.9 to z ∼ 0.1, also supporting a scenario involving major merging, though some adiabatic expansion is required. These observational results are compared to both models and simulations to further explore the implications on processes which shape and evolve BCGs/MMCGs over the past ∼7 Gyr.

Additional Information

© 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2014 May 1. Received 2014 May 1; in original form 2013 September 25. We are grateful to the anonymous referee for his/her interesting comments that made us improved the paper significantly. We thank Jeff Newman and Michael Cooper for guidance with the SPEC2D reduction pipeline and for the many useful suggestions and modifications necessary to reduce our DEIMOS data. We also thank the Keck II support astronomers for their dedication, knowledge, and ability to impart that knowledge to us at even the most unreasonable of hours. BA thanks Mamen Argudo for her help with the SDSS CasJob, Chien Peng for useful suggestions on the surface brightness analysis, Txitxo Benítez for support and suggestions and the Laboratoire d'Astrophysique de Marseille (LAM) for kindly hosting her during her visit. BCL thanks Carl Sagan and C. S. Lewis for helping to start this journey of mere observations. BA acknowledges the support from Junta de Andalucía, through the Excellence Project P08-TIC-3531 and the SpanishMinistry for Science and Innovation, through grants AYA2010-22111-C03-01 and CSD2007-00060. Part of this work was supported by funding from the European Research Council Advanced Grant ERC-2010-AdG-268107-EARLY. In addition, BCL acknowledges the support from the National Science Foundation under grant AST-0907858 and by NASA through a grant from the Space Telescope Science Institute (HST-GO-11003), which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. Portions of this work were based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. A part of this work was based on data obtained by the SDSS, which is managed by the Astrophysical Research Consortium for the Participating Institutions. Funding for the SDSS has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS website is http://www.sdss.org/. A portion of the spectrographic data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We wish to thank the indigenous Hawaiian community for allowing us to be guests on their sacred mountain; we are most fortunate to be able to conduct observations from this site.

Attached Files

Published - MNRAS-2014-Ascaso-589-615.pdf

Supplemental Material - 1309.6643v2.pdf


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