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Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/68141
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- The DEEP2 galaxy redshift survey: evolution of the colour-density relation at 0.4 < z < 1.35
- Cooper, Michael C.; Newman, Jeffery A.; Coil, Alison L.; Croton, Darren J.; Gerke, Brian F.; Yan, Renbin; Davis, Marc; Faber, S. M.; Guhathakurta, Puragra; Koo, David C.; Weiner, Benjamin J.; Willmer, Christopher N. A.
- Using a sample of 19 464 galaxies drawn from the DEEP2 Galaxy Redshift Survey, we study the relationship between galaxy colour and environment at 0.4 < z < 1.35 . We find that the fraction of galaxies on the red sequence depends strongly on local environment out to z > 1 , being larger in regions of greater galaxy density. At all epochs probed, we also find a small population of red, morphologically early-type galaxies residing in regions of low measured overdensity. The observed correlations between the red fraction and local overdensity are highly significant, with the trend at z > 1 detected at a greater than 5σ level. Over the entire redshift regime studied, we find that the colour–density relation evolves continuously, with red galaxies more strongly favouring overdense regions at low z relative to their red-sequence counterparts at high redshift. At z≳ 1.3 , the red fraction only weakly correlates with overdensity, implying that any colour dependence to the clustering of ∼L* galaxies at that epoch must be small. Our findings add weight to existing evidence that the build-up of galaxies on the red sequence has occurred preferentially in overdense environments (i.e. galaxy groups) at z≲ 1.5 . Furthermore, we identify the epoch (z∼ 2) at which typical ∼L* galaxies began quenching and moved on to the red sequence in significant number. The strength of the observed evolutionary trends at 0 < z < 1.35 suggests that the correlations observed locally, such as the morphology–density and colour–density relations, are the result of environment-driven mechanisms (i.e. 'nurture') and do not appear to have been imprinted (by 'nature') upon the galaxy population during their epoch of formation.
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- Journal article
- Monthly Notices of the Royal Astronomical Society, Vol. 376, no. 4 (Apr 2007), pp. 1445-1459
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- Copyright © 2007 The Authors. Journal compilation copyright © 2007 Royal Astronomical Society. Accepted manuscript reproduced here in accordance with the copyright policy of the publisher. The definitive publication is available at www.interscience.wiley.com.