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Extremely red objects in the UKIDSS Ultra Deep Survey Early Data Release

Chris Simpson·Omar Almaini·Michele Cirasuolo·Jim Dunlop·Sebastien Foucaud·Paul Hirst·Rob Ivison·Mat Page·Steve Rawlings·Kaz Sekiguchi·Ian Smail·Mike Watson
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Abstract

We construct a sample of extremely red objects (EROs) within the UKIDSS Ultra Deep Survey by combining the Early Data Release with optical data from the Subaru/XMM-Newton Deep Field. We find a total of 3715 objects over 2013 sq. arcmin with R-K>5.3 and K<=20.3, which is a higher surface density than found by previous studies. This is partly due to our ability to use a small aperture in which to measure colours, but is also the result of a genuine overdensity of objects compared to other fields. We separate our sample into passively-evolving and dusty star-forming galaxies using their RJK colours and investigate their radio properties using a deep radio map. The dusty population has a higher fraction of individually-detected radio sources and a higher mean radio flux density among the undetected objects, but the passive population has a higher fraction of bright radio sources, suggesting that AGNs are more prevalent among the passive ERO population.

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Chris Simpson, Omar Almaini, Michele Cirasuolo, Jim Dunlop, Sebastien Foucaud, Paul Hirst, Rob Ivison, Mat Page, Steve Rawlings, Kaz Sekiguchi, Ian Smail, Mike Watson. 2006-08-21. Extremely red objects in the UKIDSS Ultra Deep Survey Early Data Release. https://doi.org/10.1111/j.1745-3933.2006.00235.x

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