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LoCuSS: connecting the dominance and shape of brightest cluster galaxies with the assembly history of massive clusters

Smith, Graham P. and Khosroshahi, Habib G. and Dariush, A. and Sanderson, A. J. R. and Ponman, T. J. and Stott, J. P. and Haines, C. P. and Egami, E. and Stark, D. P. (2010) LoCuSS: connecting the dominance and shape of brightest cluster galaxies with the assembly history of massive clusters. Monthly Notices of the Royal Astronomical Society, 409 (1). pp. 169-183. ISSN 0035-8711. https://resolver.caltech.edu/CaltechAUTHORS:20110112-115635152

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Abstract

We study the luminosity gap, ∆m_(12), between the first- and second-ranked galaxies in a sample of 59 massive (~10^(15)M_⊙) galaxy clusters, using data from the Hale Telescope, the Hubble Space Telescope, Chandra and Spitzer. We find that the ∆m_(12) distribution, p(∆m_(12)), is a declining function of ∆m_(12) to which we fitted a straight line: p(∆m_(12))∝−(0.13 ± 0.02)∆m_(12). The fraction of clusters with ‘large’ luminosity gaps is p(∆m_(12) ≥ 1) = 0.37 ± 0.08, which represents a 3σ excess over that obtained from MonteCarlo simulations of a Schechter function that matches the mean cluster galaxy luminosity function. We also identify four clusters with ‘extreme’ luminosity gaps, ∆m_(12) ≥ 2, giving a fraction of p(∆m_(12) ≥ 2) = 0.07^(+0.05)_(−0.03). More generally, large luminosity gap clusters are relatively homogeneous, with elliptical/discy brightest cluster galaxies (BCGs), cuspy gas density profiles (i.e. strong cool cores), high concentrations and low substructure fractions. In contrast, small luminosity gap clusters are heterogeneous, spanning the full range of boxy/elliptical/discy BCG morphologies, the full range of cool core strengths and dark matter concentrations, and have large substructure fractions. Taken together, these results imply that the amplitude of the luminosity gap is a function of both the formation epoch and the recent infall history of the cluster. ‘BCG dominance’ is therefore a phase that a cluster may evolve through and is not an evolutionary ‘cul-de-sac’. We also compare our results with semi-analytic model predictions based on the Millennium Simulation. None of the models is able to reproduce all of the observational results on ∆m_(12), underlining the inability of the current generation of models to match the empirical properties of BCGs. We identify the strength of active galactic nucleus feedback and the efficiency with which cluster galaxies are replenished after they merge with the BCG in each model as possible causes of these discrepancies.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1111/j.1365-2966.2010.17311.xDOIArticle
ORCID:
AuthorORCID
Smith, Graham P.0000-0003-4494-8277
Haines, C. P.0000-0002-8814-8960
Additional Information:© 2010 The Authors. Journal compilation © 2010 RAS. Accepted 2010 July 6. Received 2010 July 2; in original form 2009 October 21. Article first published online: 6 Oct. 2010. We acknowledge helpful comments from the anonymous referee. We thank our LoCuSS collaborators, in particular Alastair Edge, Victoria Hamilton-Morris, Jean-Paul Kneib, Yuying Zhang and Nobuhiro Okabe, for encouragement, assistance and many stimulating discussions. HGK, GPS, AJRS, TJP and JPS acknowledge support from PPARC and latterly from STFC. GPS acknowledges support from the Royal Society. GPS thanks Andrew Benson, Richard Bower, Gabriella de Lucia and Malcolm Bremer for helpful discussions and comments; Kevin Bundy, Brad Cenko, Chris Conselice, Richard Ellis, Avishay Gal-Yam, Sean Moran, David Sand and Keren Sharon for assistance with acquiring some of the nearinfrared data presented in this paper; and Rick Burruss and Jeff Hickey for their support at Palomar Observatory.
Funders:
Funding AgencyGrant Number
Particle Physics and Astronomy Research Council (PPARC)UNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Royal SocietyUNSPECIFIED
Subject Keywords:gravitational lensing: strong – galaxies: clusters: general – galaxies: elliptical and lenticular, cD – galaxies: haloes – X-rays: galaxies
Issue or Number:1
Record Number:CaltechAUTHORS:20110112-115635152
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20110112-115635152
Official Citation:Smith, G. P., Khosroshahi, H. G., Dariush, A., Sanderson, A. J. R., Ponman, T. J., Stott, J. P., Haines, C. P., Egami, E. and Stark, D. P. (2010), LoCuSS: connecting the dominance and shape of brightest cluster galaxies with the assembly history of massive clusters. Monthly Notices of the Royal Astronomical Society, 409: 169–183. doi: 10.1111/j.1365-2966.2010.17311.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21732
Collection:CaltechAUTHORS
Deposited By: Benjamin Perez
Deposited On:12 Jan 2011 22:19
Last Modified:16 Nov 2019 00:36

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