Journal Article

Hierarchical models of high-redshift galaxies with thermally pulsing asymptotic giant branch stars: comparison with observations

Chiara Tonini, Claudia Maraston, Daniel Thomas, Julien Devriendt and Joseph Silk

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 403, issue 4, pages 1749-1758
Published in print April 2010 | ISSN: 0035-8711
Published online April 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2009.16231.x
Hierarchical models of high-redshift galaxies with thermally pulsing asymptotic giant branch stars: comparison with observations

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In a recent paper, we presented the first semi-analytic model of galaxy formation in which the thermally pulsing asymptotic giant branch (TP-AGB) phase of stellar evolution has been fully implemented. Here, we address the comparison with observations, and show how the TP-AGB recipe affects the performance of the model in reproducing the colours and near-infrared luminosities of high-redshift galaxies. We find that the semi-analytic model with the TP-AGB better matches the colour–magnitude and colour–colour relations at z∼ 2, both for nearly passive and for star-forming galaxies. The model with TP-AGB produces star-forming galaxies with red VK colours, thus revising the unique interpretation of high-redshift red objects as ‘red and dead’. We also show that without the TP-AGB the semi-analytic model fails at reproducing the observed colours, a situation that cannot be corrected by dust reddening. We also explore the effect of nebular emission on the predicted colour–magnitude relation of star-forming galaxies, to conclude that it does not play a significant role in reddening their colours, at least in the range of star-formation rates covered by the model. Finally, the rest-frame K-band luminosity function at z∼ 2.5 is more luminous by almost 1 mag. This indicates that the active galactic nuclei feedback recipe that is adopted to regulate the high-mass end of the luminosity function should be sophisticated to take the effect of the stellar populations into account at high redshifts.

Keywords: galaxies: evolution; galaxies: formation; galaxies: fundamental parameters; galaxies: high-redshift; galaxies: luminosity function, mass function; infrared: galaxies

Journal Article.  7835 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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