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Statistical analysis of the X-ray emission properties of type-1 AGN in the XMM-2dF Wide Angle Survey Silvia Mateos Leicester University (UK) Leicester University (UK) M.G. Watson, J. A. Tedds and Y. Xu Leicester University (UK) Mullard Space Science Laboratory-UCL (UK) M. Page Mullard Space Science Laboratory-UCL (UK) Instituto de Física de Cantabria CSIC-UC (Spain F.J. Carrera and A. Corral Instituto de Física de Cantabria CSIC-UC (Spain) Astrophysikalisches Institut Potsdam (Germany) A. Schwope and M. Krumpe Astrophysikalisches Institut Potsdam (Germany)
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Motivation The sample of type-1 AGN in XMM-2dF Wide Angle Survey is one of the largest samples of X-ray selected type-1 AGN assembled so far Unique resource to characterise the X-ray emission properties of the dominant population of sources at fluxes ~10 -14 erg cm -2 s -1, where the bulk of the Cosmic X-ray Background (CXRB) emission originates: Broad band continuum shape and intrinsic dispersion Fraction of X-ray absorbed type-1 AGN and distribution of absorbing column densities Dependence of emission properties on the X-ray luminosity of the objects and redshift
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XMM-2dF Wide Angle Survey 2dF optical multi-fibre spectroscopy on the AAT obtained for 68 XMM- Newton fields (t exp ~ few tens of ksec) over a total area >15 deg 2 More than 3000 sources with X-ray fluxes above ~10 -14 cgs and optical counterparts brighter than V~21 observed and reduced 978 serendipitous X-ray sources with 0.5-4.5 keV flux >10 -14 erg cm -2 s -1 spectroscopically identified TypeNumber BLAGN641 (65.5%) NELG157 (16%) Gal57 (5.8%) Stars123 (12.6%)
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Type-1 AGN in the XMM-2dF Wide Angle Survey Typical fluxes ~break in the X-ray source counts 2-10 keV flux 496 type-1 AGN with ≥75 EPIC counts selected for X-ray spectral analysis
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X-ray spectral analysis Power law and absorbed power law (both absorbed by the Galaxy) models fitted to all 0.2-12 keV X-ray spectra Single-source analysis of brightest objects (down to 200 EPIC counts, 300 objects) now completed F-test significance ≥95% to accept additional spectral components Overal results of spectral fits: 381 (~77%) best fitted with a power law 37 (~7.5%) objects with detected absorption 78 (~15.7%) objects with detected soft excess emission
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=1.95 ± 0.04 =0.20 ± 0.03 Broad band continuum shape(I) The 0.2-12 keV X-ray spectra type-1 AGN best fitted with a power law of ~1.9. However significant intrinsic dispersion in measured values detected
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Broad band continuum shape(II) No clear cosmic evolution of the mean continuum shape of type-1 AGN up to z~3
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Broad band continuum shape(III) The 0.2-12 keV continuum shape does not show obvious dependence with X-ray luminosity from 10 43 -10 45 erg s -1 2-10 keV lum
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Excess absorption in type-1 AGN(I) No correlation between and N H Typical values of absorbing column density N H ~ few 10 21 cm -2 For sources with N H >10 22 cm -2 existing correlation of optical and X-ray emission properties unclear X-ray absorption detected (F-test≥95%) in 37 type-1 AGN (~7%)
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Excess absorption in type-1 AGN(II) Detection of X-ray absorption in type-1AGN does not occur at any preferred X-ray luminosity or redshift = 44.17 unabsorbed type-1 AGN = 44.17 unabsorbed type-1 AGN = 44.25 absorbed type-1 AGN = 44.25 absorbed type-1 AGN
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No evident dependence of X-ray absorbing column densities detected in type-1 AGN with luminosity or redshift Excess absorption in type-1 AGN(III)
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Conclusions 0.2-12 keV emission of most type-1 AGN best fitted with a power law mean continuum shape ~1.95 mean continuum shape ~1.95 intrinsic dispersion ~0.20 intrinsic dispersion ~0.20 Continuum shape no significant evolution up to redshifts of ~3 no significant evolution up to redshifts of ~3 no luminosity dependence in range 10 43 -10 45 erg s -1 no luminosity dependence in range 10 43 -10 45 erg s -1 X-ray absorption detected in ~7% of our type-1 AGN absorbed type-1 AGN do not seem to occur preferentially atabsorbed type-1 AGN do not seem to occur preferentially at any particular redshift or luminosity any particular redshift or luminosity no obvious dependence of N H with redshift or luminosity no obvious dependence of N H with redshift or luminosity typical values ~10 21 cm -2 –a substantial fraction with detected typical values ~10 21 cm -2 –a substantial fraction with detected N H >10 22 cm -2 N H >10 22 cm -2 Existing correlation of optical and X-ray properties unclear Existing correlation of optical and X-ray properties unclear
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Broad band continuum shape(IV) The hardening of with X-ray flux known to be mostly due to undetected X-ray absorption 2-10 keV flux 0.5-2 keV flux
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