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The (un)resolved X-ray background in the Lockman Hole

M. A. Worsley·A. C. Fabian·X. Barcons·S. Mateos·G. Hasinger·H. Brunner
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Abstract

Most of the soft and a growing fraction of the harder X-ray background has been resolved into emission from point sources, yet the resolved fraction above 7 keV has only been poorly constrained. We use ~700 ks of XMM-Newton observations of the Lockman Hole and a photometric approach to estimate the total flux attributable to resolved sources in a number of different energy bands. We find the resolved fraction of the X-ray background to be ~90 per cent below 2 keV but it decreases rapidly at higher energies with the resolved fraction above ~7 keV being only ~50 per cent. The integrated X-ray spectrum from detected sources has a slope of Gamma~1.75, much softer than the Gamma=1.4 of the total background spectrum. The unresolved background component has the spectral signature of highly obscured AGN.

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M. A. Worsley, A. C. Fabian, X. Barcons, S. Mateos, G. Hasinger, H. Brunner. 2004-07-08. The (un)resolved X-ray background in the Lockman Hole. https://doi.org/10.1111/j.1365-2966.2004.08142.x

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