Contribution of Unresolved Point Sources to the Diffuse X-ray Background below 1 keV

Abstract

We present here the analysis of X-rays point sources detected in several observations available in the XMM-Newton public archive. We focused, in particular, on energies below 1 keV, which are of particular relevance to the understanding of the Diffuse X-ray Background. The average field of all the exposures is 0.09 deg^-2. We reached an average flux sensitivity of 5.8x10^-16 erg s^-1 cm^-2 in the soft band (0.5-2.0 keV) and 2.5x10^-16 erg s^-1 cm^-2 in the very soft band (0.4-0.6 keV). In this paper we discuss the logN-logS results, the contribution to the integrated X-ray sky flux, and the properties of the cumulative spectrum from all sources. In particular, we found an excess flux at around 0.5 keV in the composite spectrum of faint sources. The excess seems to be a general property of all the fields observed suggesting an additional class of weak sources is contributing to the X-ray emission at these energies. Combining our results with previous investigations we have also quantified the contribution of the individual components of the diffuse X-ray Background in the 3/4 keV band.

Accepted for publication in ApJ; 27 pages, 8 figures

References in corpus (17)

• First Results from the X-ray and Optical Survey of the Chandra Deep Field South
• Resolving the extragalactic hard X-ray background
• A High Spectral Resolution Observation of the Soft X-ray Diffuse Background with Thermal Detectors
• The XMM-Newton EPIC Background: Production of Background Maps and Event Files
• The HELLAS2XMM survey: I. The X-ray data and the Log(N)-Log(S)
• Exploring the X-ray Sky with the XMM-Newton Bright Serendipitous Survey
• High precision X-ray logN-logS distributions: implications for the obscured AGN population
• Suzaku Observations of the Local and Distant Hot ISM
• Xmm-Newton Observations of the Diffuse X-ray Background
• Comparing Suzaku and XMM-Newton Observations of the Soft X-ray Background: Evidence for Solar Wind Charge Exchange Emission
• An XMM-Newton Observation of the Local Bubble Using a Shadowing Filament in the Southern Galactic Hemisphere
• Chandra Observations of MBM12 and Models of the Local Bubble
• X-Ray Constraints on the Warm_hot Intergalactic Medium
• The stellar content of the XMM-Newton Bright Serendipitous Survey
• Evidence for the Missing Baryons in the Angular Correlation of the Diffuse X-ray Background
• X-Ray Emission from the Warm Hot Intergalactic Medium
• Accuracy of Mesh Based Cosmological Hydrocodes: Tests and Corrections

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