Substructures in hydrodynamical cluster simulations |
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| Authors: | K Dolag S Borgani G Murante V Springel |
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| Institution: | Institut de Ciències de l'Espai (CSIC/IEEC), F. de Ciencies, Torre C5 Par 2a, UAB, Bellaterra, 08193 Barcelona, Spain;Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE |
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| Abstract: | We present predictions for the abundance and nature of extremely red objects (EROs) in the Λ cold dark matter model. EROs are red, massive galaxies observed at z ≥ 1 and their numbers and properties pose a challenge to hierarchical galaxy formation models. We compare the predictions from two published models, one of which invokes a 'superwind' to regulate star formation in massive haloes and the other which suppresses gas cooling in haloes through 'radio-mode' active galactic nucleus (AGN) feedback. The superwind model underestimates the number counts of EROs by an order of magnitude, whereas the radio-mode AGN feedback model gives excellent agreement with the number counts and redshift distribution of EROs. In the AGN feedback model the ERO population is dominated by old, passively evolving galaxies, whereas observations favour an equal split between old galaxies and dusty starbursts. Also, the model predicts a more extended redshift distribution of passive galaxies than is observed. These comparisons suggest that star formation may be quenched too efficiently in this model. |
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| Keywords: | galaxies: evolution galaxies: formation galaxies: high-redshift cosmology: theory |
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