Journal Article

The DEEP2 Galaxy Redshift Survey: the red sequence AGN fraction and its environment and redshift dependence

Antonio D. Montero-Dorta, Darren J. Croton, Renbin Yan, Michael C. Cooper, Jeffery A. Newman, Antonis Georgakakis, Francisco Prada, Marc Davis, Kirpal Nandra and Alison Coil

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 392, issue 1, pages 125-134
Published in print January 2009 | ISSN: 0035-8711
Published online December 2008 | e-ISSN: 1365-2966 | DOI:
The DEEP2 Galaxy Redshift Survey: the red sequence AGN fraction and its environment and redshift dependence

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We measure the dependence of the active galactic nuclei (AGN) fraction on local environment at z∼ 1, using spectroscopic data taken from the DEEP2 Galaxy Redshift Survey, and Chandra X-ray data from the All-Wavelength Extended Groth Strip International Survey (AEGIS). To provide a clean sample of AGN, we restrict our analysis to the red sequence population; this also reduces additional colour–environment correlations. We find evidence that high-redshift LINERs in DEEP2 tend to favour higher density environments relative to the red population from which they are drawn. In contrast, Seyferts and X-ray selected AGN at z∼ 1 show little (or no) environmental dependencies within the same underlying population. We compare these results with a sample of local AGN drawn from the Sloan Digital Sky Survey (SDSS). Contrary to the high-redshift behaviour, we find that both LINERs and Seyferts in the SDSS show a slowly declining red sequence AGN fraction towards high-density environments. Interestingly, at z∼ 1 red sequence Seyferts and LINERs are approximately equally abundant. By z∼ 0, however, the red Seyfert population has declined relative to the LINER population by over a factor of ∼4.5. We speculate on possible interpretations of our results.

Keywords: galaxies: active; galaxies: evolution; galaxies: high-redshift; galaxies: statistics; large-scale structure of Universe

Journal Article.  7695 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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