Resolving the X-ray background

M. A. Worsley, A. C. Fabian, D. M. Alexander, F. E. Bauer, W. N. Brandt, G. Hasinger, B. D. Lehmer

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations


We have stacked the X-ray emission from X-ray-detected sources in ∼ 3.8 Ms of Chandra Deep Field and XMM-Newton Lockman Hole observations. The fraction of the X-ray background which can be resolved into point sources is ∼ 70-90% up to 4 keV. In the 6-8 keV band this fraction decreases to ∼ 50-70% and XMM-Newton indicates only ∼ 40-60% in the 8-12 keV range. The unresolved fraction is consistent with an undiscovered population of highly obscured AGN. To attempt to uncover this population we proceeded to stack the X-ray emission from the X-ray-undetected optical sources in the Chandra Deep Fields, using Hubble source positions from the Great Observatories Origins Deep Survey. In the 0.5-6 keV range the stacked-source emission corresponds to the remaining 10-20% of the X-ray background. In the 6-8 keV band we find upper limits to the stacked X-ray flux consistent with the remaining ∼ 40% of the background, but the errors are too large to claim a detection of the obscured AGN population.

Original languageEnglish (US)
Title of host publicationAstrophysical Sources of High Energy Particles and Radiation
Number of pages6
StatePublished - Nov 22 2005
EventAstrophysical Sources of High Energy Particles and Radiation - Torun, Poland
Duration: Jun 20 2005Jun 24 2005

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


OtherAstrophysical Sources of High Energy Particles and Radiation

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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