Almeida, C. and Baugh, C. M. and Wake, D. A. and Lacey, C. G. and Benson, A. J. and Bower, R. G. and Pimbblet, K. (2008) Luminous red galaxies in hierarchical cosmologies. Monthly Notices of the Royal Astronomical Society, 386 (4). pp. 2145-2160. ISSN 0035-8711 http://resolver.caltech.edu/CaltechAUTHORS:ALMmnras08
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Luminous red galaxies (LRGs) are much rarer and more massive than L* galaxies. Coupled with their extreme colours, LRGs therefore provide a demanding testing ground for the physics of massive galaxy formation. We present the first self-consistent predictions for the abundance and properties of LRGs in hierarchical structure formation models. We test two published models which use quite different mechanisms to suppress the formation of massive galaxies: the Bower et al. model which invokes 'active galactic nuclei (AGN) feedback' to prevent gas from cooling in massive haloes and the Baugh et al. model which relies upon a 'superwind' to eject gas before it is turned into stars. Without adjusting any parameters, the Bower et al. model gives an excellent match to the observed luminosity function of LRGs in the Sloan Digital Sky Survey (with a median redshift of z=0.24 ) and to their clustering; the Baugh et al. model is less successful in these respects. Both models fail to match the observed abundance of LRGs at z= 0.5 to better than a factor of ≈2. In the models, LRGs are typically bulge-dominated systems with stellar masses of ≈2 × 10^11 h^−1 M⊙ and velocity dispersions of σ∼ 250 km s^−1 . Around half of the stellar mass in the model LRGs is already formed by z∼ 2.2 and is assembled into one main progenitor by z∼ 1.5; on average, only 25 per cent of the mass of the main progenitor is added after z∼ 1. LRGs are predicted to be found in a wide range of halo masses, a conclusion which relies on properly taking into account the scatter in the formation histories of haloes. Remarkably, we find that the correlation function of LRGs is predicted to be a power law down to small pair separations, in excellent agreement with observational estimates. Neither the Bower et al. nor the Baugh et al. model is able to reproduce the observed radii of LRGs.
|Additional Information:||© 2008 The Authors. Journal compilation © 2008 RAS. Accepted 2008 March 2. Received 2008 March 2; in original form 2007 October 18. Published Online: 11 April 2008. CA gratefully acknowledges support in the form of a scholarship from the Science and Technology Foundation (FCT), Portugal. CMB is supported by the Royal Society. AJB acknowledges support from the Gordon and Betty Moore Foundation. This work was supported, in part, by a rolling grant from PPARC. We thank the referee for providing a detailed and helpful report.We acknowledge comments and suggestions from Bob Nichol, Nic Ross and Donald Schneider, and the contributions of Shaun Cole, Carlos Frenk, John Helly and Rowena Malbon to the development of the GALFORM code.|
|Subject Keywords:||galaxies: elliptical and lenticular, cD; galaxies : evolution; cosmology : theory; large-scale structure of Universe|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||05 Feb 2009 07:55|
|Last Modified:||26 Dec 2012 10:46|
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