Near-infrared evolution of brightest cluster galaxies in the most X-ray luminous clusters since z = 1

Creators: Stott, J. P.; Edge, A. C.; Smith, G. P.; Swinbank, A. M.; Ebeling, H.

Abstract

We investigate the near-infrared evolution of brightest cluster galaxies (BCGs) from a sample of rich galaxy clusters since z ~ 1. By employing an X-ray selection of L_X > 10^(44) erg s^(−1), we limit environmental effects by selecting BCGs in comparably high-density regions. We find a positive relationship between X-ray and near-infrared luminosity for BCGs in clusters with L_X > 5 × 10^(44) erg s^(−1). Applying a correction for this relation, we reduce the scatter in the BCG absolute magnitude by a factor of 30 per cent. The near-infrared J − K colour evolution demonstrates that the stellar population in BCGs has been in place since at least z = 2, and that we expect a shorter period of star formation than that predicted by current hierarchical merger models. We also confirm that there is a relationship between 'blue' J − K colour and the presence of BCG emission lines associated with star formation in cooling flows.

Additional Information

© 2008 The Authors. Accepted 2007 November 29. Received 2007 November 28; in original form 2007 September 28. We thank the referee for their useful comments which have improved the clarity of this paper. We also thank Carlton Baugh, Richard Bower and Sarah Brough for useful discussions. JPS acknowledges support through a Particle Physics and Astronomy Research Council Studentship. GPS acknowledges financial support from the Royal Society. This publication makes use of data products from the Two-Micron All-Sky Survey, which is a joint project of the University of Massachusetts and the IR Processing and Analysis Centre/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This work is based in part on data obtained as part of the UKIRT Infrared Deep Sky Survey. The United Kingdom Infrared Telescope is operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the United Kingdom. This work is based partly on observations obtained at the Hale 200-inch telescope at Palomar Observatory.

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