XMM-Newton observation of the Chandra Deep Field-South: Statistical treatment of faint source spectra

Abstract

We present first results of the X-ray spectral analysis of the 500 ksec deep survey obtained with XMM-Newton on the Chandra Deep Field South (CDFS). Statistical distributions of spectral index and intrinsic absorption are derived for a sample containing 70 sources with a count limit of 100 (flux limit in the [2-10] keV band of 8.9 $\times 10^{-16}$ erg cm${}^{-2}$ s${}^{-1}$), of which 44 have redshift identification. We observe a separation between the type-1 and the type-2 AGN in diagnostics involving different X-ray parameters. Using the subsample with known $z$, we show that this separation between the AGN populations is a consequence of different absorption column densities. The two populations have the same average spectral index, $<\Gamma >=2\pm 0.1$. We present integrated spectrum for the most distant type-2 QSO whith strong X-ray absorption and a clear soft excess; we obtained the best fit for these objects with two difference models: a scattering model and a double power law model. We also confirm a progressive hardening for the combined integrated spectra for faint objects which at first was noted by \cite{toz01a}. Our results shown a clear evolution of decrease of $<\Gamma >$ with decreasing flux in the hard 2-10 keV band. However, we detect not only a regular increase of $<\Gamma >$ for different subsamples of fluxes in comparison with Chandra results, but also an internal discrepancy of the values, if we fitted in the different energy bands.

arXiv comment6 pages, 6 figures. Proceedings of the symposium "The Restless High-Energy Universe", 5-8 May 2003, Amsterdam, The Netherlands

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• XMM-Newton observations of the Lockman Hole IV: spectra of the brightest AGN
• Mid-infrared Properties and Color Selection for X-ray Detected AGN in the MUSYC ECDF-S field
• The distribution of absorption in AGN detected in the XMM-Newton observations of the CDFS
• Variability-selected active galactic nuclei from supernova search in the Chandra deep field south
• Can the unresolved X-ray background be explained by emission from the optically-detected faint galaxies of the GOODS project?
• Relativistic outflow in CXO CDFS J033260.0-274748