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

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.

6 pages, 6 figures, MNRAS Letters, in press, changed to reflect accepted version

References in corpus (30)

• Cosmological Evolution of the Hard X-ray AGN Luminosity Function and the Origin of the Hard X-ray Background
• The Chandra Deep Field-North Survey. XIII. 2 Ms Point-Source Catalogs
• The Chandra Deep Field South: the 1 Million Second
• First Results from the X-ray and Optical Survey of the Chandra Deep Field South
• Resolving the extragalactic hard X-ray background
• The Spectrum of Diffuse Cosmic Hard X-Rays Measured with HEAO-1
• The 2-8 keV cosmic X-ray background spectrum as observed with XMM-Newton
• XMM-Newton observation of the Lockman Hole; I. The X-ray Data
• The Chandra Deep Field North Survey. V. 1 Ms Source Catalogs
• The resolved fraction of the Cosmic X-ray Background
• The Chandra Deep Survey of the Hubble Deep Field North Area. II. Results from the Caltech Faint Field Galaxy Redshift Survey Area
• A Classic Type 2 QSO
• X-ray, Optical, and Infrared Imaging and Spectral Properties of the 1 Ms Chandra Deep Field North Sources
• New Results from the X-ray and Optical Survey of the Chandra Deep Field South: The 300ks Exposure
• Testing current synthesis models of the X-ray background
• The X-ray spectra of Compton-thick Seyfert 2 galaxies as seen by BeppoSAX
• Chandra Detection of a TypeII Quasar at z=3.288
• The Chandra Deep Survey of the Hubble Deep Field North Area. IV. An Ultradeep Image of the HDF-N
• X-ray Sources in the Hubble Deep Field Detected by Chandra
• XMM-Newton observations of the Lockman Hole V: time variability of the brightest AGN
• Confusion errors in astrometry and counterpart association
• X-ray background synthesis: the infrared connection
• Faint Source Counts from Off-source Fluctuation Analysis on Chandra Observations of the Hubble Deep Field-North
• Powerful obscured AGN among X-ray hard, optically-dim serendipitous Chandra sources
• The deepest X-ray look at the Universe
• The soft X-ray background: evidence for widespread disruption of the gas halos of galaxy groups
• On the detectability of distant Compton-thick obscured quasars
• The BMW Detection Algorithm applied to the Chandra Deep Field south: deeper and deeper
• The diffuse X-ray background
• Optical and near-infrared observations of hard serendipitous Chandra sources

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• Balancing the Cosmic Energy Budget: The Cosmic X-ray Background, Blazars and the Compton Thick AGN Fraction
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• The XMM-SSC survey of hard-spectrum XMM-Newton sources 1: optically bright sources
• A multiwavelength study of near- and mid-infrared selected galaxies at high redshift: ERGs, AGN-identification and the contribution from dust
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