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Title: The unresolved hard X-ray background: the missing source population implied by the Chandra and XMM-Newton deep fields
Authors: Worsley, M. A.
Fabian, A. C.
Bauer, F. E.
Alexander, D. M.
Hasinger, G.
Mateos, S.
Brunner, H.
Brandt, W. N.
Schneider, D. P.
First Published: 11-Mar-2005
Publisher: Oxford University Press (OUP), Royal Astronomical Society
Citation: Monthly Notices of the Royal Astronomical Society, 2006, 357 (4), pp.1281-1287
Abstract: We extend our earlier work on X-ray source stacking in the deep XMM—Newton observation of the Lockman Hole, to the 2-Ms Chandra Deep Field North (CDF-N) and the 1-Ms Chandra Deep Field South (CDF-S). The XMM—Newton work showed the resolved fraction of the X-ray background (XRB) to be ∼80–100 per cent at ≲ 2 keV but this decreased to only ∼50 per cent above ∼8 keV. The CDF-N and CDF-S probe deeper, and are able to fill in some of the missing fraction in the 4–6 keV range, but the resolved fraction in the 6–8 keV band remains only ∼60 per cent, confirming the trend seen with XMM—Newton. The missing XRB component has a spectral shape that is consistent with a population of highly obscured active galactic nuclei (AGN) at redshifts ∼0.5–1.5 and with absorption column densities of ∼1023–1024 cm−2.
DOI Link: 10.1111/j.1365-2966.2005.08731.x
ISSN: 0035-8711
Type: Article
Rights: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, Copyright 2005 RAS Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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