Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/238031

Title

The evolution of brightest cluster galaxies in a hierarchical universe

Author(s)

Tonini, Chiara;  Bernyk, Maksym;  Croton, Darren;  Maraston, Claudia;  Thomas, Daniel

Abstract

We investigate the evolution of brightest cluster galaxies (BCGs) from redshift z ~ 1.6 to z = 0. We upgrade the hierarchical semi-analytic model of Croton et al. with a new spectro-photometric model that produces realistic galaxy spectra, making use of the Maraston stellar populations and a new recipe for the dust extinction. We compare the model predictions of the K-band luminosity evolution and the J – K, V – I, and I – K color evolution with a series of data sets, including those of Collins et al. who argued that semi-analytic models based on the Millennium simulation cannot reproduce the red colors and high luminosity of BCGs at z > 1. We show instead that the model is well in range of the observed luminosity and correctly reproduces the color evolution of BCGs in the whole redshift range up to z ~ 1.6. We argue that the success of the semi-analytic model is in large part due to the implementation of a more sophisticated spectro-photometric model. An analysis of the model BCGs shows an increase in mass by a factor of 2-3 since z ~ 1, and star formation activity down to low redshifts. While the consensus regarding BCGs is that they are passively evolving, we argue that this conclusion is affected by the degeneracy between star formation history and stellar population models used in spectral energy distribution fitting, and by the inefficacy of toy models of passive evolution to capture the complexity of real galaxies, especially those with rich merger histories like BCGs. Following this argument, we also show that in the semi-analytic model the BCGs show a realistic mix of stellar populations, and that these stellar populations are mostly old. In addition, the age-redshift relation of the model BCGs follows that of the universe, meaning that given their merger history and star formation history, the ageing of BCGs is always dominated by the ageing of their stellar populations. In a ΛCDM universe, we define such evolution as 'passive in the hierarchical sense.'

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing

Source

Astrophysical Journal, Vol. 759, no. 1 (Nov 2012), article no. 43

Publication year

2012

FOR Code(s)

0201 Astronomical and Space Sciences;  0305 Organic Chemistry;  0306 Physical Chemistry (Incl. Structural)

Keyword(s)

Fundamental parameters;  Galaxy clusters;  Galaxy evolution;  Galaxy photometry;  Star formation;  Stellar content

Publisher

Institute of Physics Publishing

ISSN

0004-637X

Publisher URL

http://dx.doi.org/10.1088/0004-637x/759/1/43

Copyright

Copyright © 2012 The American Astronomical Society. All rights reserved. The American Astronomical Society does not allow institutions to archive either the accepted manuscript or the published version of the article. However, you can find an earlier version of the full text here: http://arxiv.org/abs/1209.1204

Additional information

The authors acknowledge support from a Queen Elizabeth II Fellowship awarded by the Australian Research Council.

Peer reviewed