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X-UDS : the Chandra legacy survey of the UKIDSS Ultra Deep Survey field.

Kocevski, Dale D. and Hasinger, Guenther and Brightman, Murray and Nandra, Kirpal and Georgakakis, Antonis and Cappelluti, Nico and Civano, Francesca and Li, Yuxuan and Li, Yanxia and Aird, James and Alexander, David M. and Almaini, Omar and Brusa, Marcella and Buchner, Johannes and Comastri, Andrea and Conselice, Christopher J. and Dickinson, Mark A. and Finoguenov, Alexis and Gilli, Roberto and Koekemoer, Anton M. and Miyaji, Takamitsu and Mullaney, James R. and Papovich, Casey and Rosario, David and Salvato, Mara and Silverman, John D. and Somerville, Rachel S. and Ueda, Yoshihiro (2018) 'X-UDS : the Chandra legacy survey of the UKIDSS Ultra Deep Survey field.', Astrophysical journal supplement series., 236 (2). p. 48.


We present the X-UDS survey, a set of wide and deep Chandra observations of the Subaru-XMM Deep/UKIDSS Ultra Deep Survey (SXDS/UDS) field. The survey consists of 25 observations that cover a total area of 0.33 deg2. The observations are combined to provide a nominal depth of ~600 ks in the central 100 arcmin2 region of the field that has been imaged with Hubble/WFC3 by the CANDELS survey and ~200 ks in the remainder of the field. In this paper, we outline the survey's scientific goals, describe our observing strategy, and detail our data reduction and point source detection algorithms. Our analysis has resulted in a total of 868 band-merged point sources detected with a false-positive Poisson probability of <1 × 10−4. In addition, we present the results of an X-ray spectral analysis and provide best-fitting neutral hydrogen column densities, N H, as well as a sample of 51 Compton-thick active galactic nucleus candidates. Using this sample, we find the intrinsic Compton-thick fraction to be 30%–35% over a wide range in redshift (z = 0.1–3), suggesting the obscured fraction does not evolve very strongly with epoch. However, if we assume that the Compton-thick fraction is dependent on luminosity, as is seen for Compton-thin sources, then our results are consistent with a rise in the obscured fraction out to z ~ 3. Finally, an examination of the host morphologies of our Compton-thick candidates shows a high fraction of morphological disturbances, in agreement with our previous results. All data products described in this paper are made available via a public website.

Item Type:Article
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Publisher statement:© 2018. The American Astronomical Society. All rights reserved.
Date accepted:29 January 2018
Date deposited:05 July 2018
Date of first online publication:14 June 2018
Date first made open access:05 July 2018

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