X-ray spectra of sources in the 13HXMM–Newton/Chandra deep field

Page, M. J.; Loaring, N. S.; Dwelly, T.; Mason, K. O.; McHardy, I. M.; Gunn, K. F.; Moss, D.; Sasseen, T.; Córdova, F. A.; Kennea, J. A.; Seymour, N.

doi:10.1111/j.1365-2966.2006.10278.x

Cited by 34 publications

(48 citation statements)

References 60 publications

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“…Because the errors on the photon index are not symmetric, we used the average value for the individual errors in each case. We obtain a mean value of Γ = 2.05 ± 0.03 with an intrinsic dispersion of σ = 0.26 ± 0.02 for the BSS and Γ = 1.98 ± 0.08 with an intrinsic dispersion of σ = 0.29 ± 0.05 for the HBSS, in agreement with previous works (Mateos et al 2010;Young et al 2009;Dadina 2008;Mainieri et al 2007;Page et al 2006;Mateos et al 2005a,b). Errors were extracted from the 1σ confidence contours.…”

Section: Photon Indexsupporting

confidence: 92%

The X-ray spectral properties of the AGN population in theXMM-Newtonbright serendipitous survey

Corral

Ceca

Caccianiga

et al. 2011

A&A

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Context. X-ray surveys are a key instrument in the study of active galactic nuclei (AGN). Thanks to their penetrating ability, X-rays are able to map the innermost regions close to the central super massive black hole (SMBH) as well as to detect and characterize its emission up to high redshift. Aims. We present here a detailed X-ray spectral analysis of the AGN belonging to the XMM-Newton bright survey (XBS). The XBS is composed of two flux-limited samples selected in the complementary 0.5−4.5 and 4.5−7.5 keV energy bands and comprising more than 300 AGN up to redshift ∼2.4. Methods. We performed an X-ray analysis following two different approaches: by analyzing individually each AGN X-ray spectrum and by constructing average spectra for different AGN types. Results. From the individual analysis, we find that there seems to be an anti correlation between the spectral index and the sources' hard X-ray luminosity, such that the average photon index for the higher luminosity sources (>10 44 erg s −1 ) is significantly (>2σ) flatter than the average for the lower luminosity sources. We also find that the intrinsic column density distribution agrees with AGN unified schemes, although a number of exceptions are found (3% of the whole sample), which are much more common among optically classified type 2 AGN. We also find that the so-called "soft-excess", apart from the intrinsic absorption, constitutes the principal deviation from a power-law shape in AGN X-ray spectra and it clearly displays different characteristics, and likely a different origin, for unabsorbed and absorbed AGN. Regarding the shape of the average spectra, we find that it is best reproduced by a combination of an unabsorbed (absorbed) power law, a narrow Fe Kα emission line and a small (large) amount of reflection for unabsorbed (absorbed) sources. We do not significantly detect any relativistic contribution to the line emission and we compute an upper limit for its equivalent width (EW) of 230 eV at the 3σ confidence level. Finally, by dividing the type 1 AGN sample into high-and low-luminosity sources, we marginally detect a decrease in the narrow Fe Kα line EW and in the amount of reflection as the luminosity increases, the "so-called" Iwasawa-Taniguchi effect.

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Section: Photon Indexsupporting

confidence: 92%

The X-ray spectral properties of the AGN population in theXMM-Newtonbright serendipitous survey

Corral

Ceca

Caccianiga

et al. 2011

A&A

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130

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“…These values are in excellent agreement with recent measurements of the mean photon index and intrinsic dispersion for type-1 AGN found in the literature (e.g. Young et al 2009;Dadina 2008;Mainieri et al 2007;Page et al 2006;Mateos et al 2005a,b). We note that hard X-ray selected samples ( > ∼ 20 keV) from the INTEGRAL and Swift satellites report marginally flatter spectral slopes for bright type-1 AGN, Γ ∼ 1.7−1.8 (Molina et al 2009;Winter et al 2009;Panessa et al 2008).…”

Section: The Broad Band X-ray Continuumsupporting

confidence: 92%

“…Using a fixed spectral slope of Γ = 1.9 we detected substantial X-ray absorption in all sources with typical measured column densities N H ∼ a few × 10 22 cm −2 . Previous studies of type-1 AGN selected in the optical (Piconcelli et al 2005) and X-ray band (Mainieri et al 2007;Page et al 2006;Mateos et al 2005b;Mateos et al 2005a;Caccianiga et al 2004;Perola et al 2004;Barcons et al 2002) report a fraction of absorbed type-1 AGN of 10% or less, i.e. marginally higher than our reported value, however most of these studies used lower confidence thresholds when applying the F-test.…”

Section: X-ray Absorptioncontrasting

confidence: 71%

The XMM-NewtonWide Angle Survey (XWAS): the X-ray spectrum of type-1 AGN

Mateos¹,

Carrera

Page

et al. 2010

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Aims. We discuss the broad band X-ray properties of one of the largest samples of X-ray selected type-1 AGN to date (487 objects in total), drawn from the XMM-Newton Wide Angle Survey (XWAS). The objects presented in this work cover 2−10 keV (rest-frame) luminosities from ∼10 42 −10 45 erg s −1 and are detected up to redshift ∼4. We constrain the overall properties of the broad band continuum, soft excess and X-ray absorption, along with their dependence on the X-ray luminosity and redshift. We discuss the implications for models of AGN emission. Methods. We fitted the observed 0.2−12 keV broad band spectra with various models to search for X-ray absorption and soft excess. The F-test was used with a significance threshold of 99% to statistically accept the detection of additional spectral components. Results. We constrained the mean spectral index of the broad band X-ray continuum to Γ = 1.96 ± 0.02 with intrinsic dispersion σ Γ = 0.27 +0.01 −0.02 . The continuum becomes harder at faint fluxes and at higher redshifts and hard (2−10 keV) luminosities. The dependence of Γ with flux is likely due to undetected absorption rather than to spectral variation. We found a strong dependence of the detection efficiency of objects on the spectral shape. We expect this effect to have an impact on the measured mean continuum shapes of sources at different redshifts and luminosities. We detected excess absorption in > ∼ 3% of our objects, with rest-frame column densities ∼a few ×10 22 cm −2 . The apparent mismatch between the optical classification and X-ray properties of these objects is a challenge for the standard orientation-based AGN unification model. We found that the fraction of objects with detected soft excess is ∼36%. Using a thermal model, we constrained the soft excess mean rest-frame temperature and intrinsic dispersion to kT ∼ 100 eV and σ kT ∼ 34 eV. The origin of the soft excess as thermal emission from the accretion disk or Compton scattered disk emission is ruled out on the basis of the temperatures detected and the lack of correlation of the soft excess temperature with the hard X-ray luminosity over more than 2 orders of magnitude in luminosity. Furthermore, the high luminosities of the soft excess rule out an origin in the host galaxy.

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“…This, in addition to the fact that ALGs are less absorbed than NELGs, is an indication that the non-active optical appearance of the ALGs is most likely due to a host galaxy effect, i.e. the emission lines and AGN continnum are outshone by the stellar continuum as also found in Moran et al (2002); Severgnini et al (2003); Mateos et al (2005); Page et al (2006).…”

Section: X-ray Colour Distributionmentioning

confidence: 71%

TheXMM-NewtonWide Angle Survey (XWAS)

Esquej

Page

Carrera

et al. 2013

A&A

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Aims. This programme is aimed at obtaining one of the largest X-ray selected samples of identified active galactic nuclei to date in order to characterise such a population at intermediate fluxes, where most of the Universe's accretion power originates. We present the XMM-Newton Wide Angle Survey (XWAS), a new catalogue of almost a thousand X-ray sources spectroscopically identified through optical observations. Methods. A sample of X-ray sources detected in 68 XMM-Newton pointed observations was selected for optical multi-fibre spectroscopy. Optical counterparts and corresponding photometry of the X-ray sources were obtained from the SuperCOSMOS Sky Survey. Candidates for spectroscopy were initially selected with magnitudes down to R ∼ 21, with preference for X-ray sources having a flux F 0.5−4.5 keV ≥ 10 −14 erg s −1 cm −2 . Optical spectroscopic observations were made using the Two Degree Field of the Anglo Australian Telescope, and the resulting spectra were classified based on optical emission lines. Results. We have identified through optical spectroscopy 940 X-ray sources over Ω ∼ 11.8 deg 2 of the sky. Source populations in our sample can be summarised as 65% broad line active galactic nuclei (BLAGN), 16% narrow emission line galaxies (NELGs), 6% absorption line galaxies (ALGs) and 13% stars. An active nucleus is also likely to be present in the large majority of the X-ray sources spectroscopically classified as NELGs or ALGs. Sources lie in high-galactic latitude (|b| > 20 deg) XMM-Newton fields mainly in the southern hemisphere. Owing to the large parameter space in redshift (0 ≤ z ≤ 4.25) and flux (10 −15 ≤ F 0.5−4.5 keV ≤ 10 −12 erg s −1 cm −2 ) covered by the XWAS this work provides an excellent resource for the further study of subsamples and particular cases. The overall properties of the extragalactic objects are presented in this paper. These include the redshift and luminosity distributions, optical and X-ray colours and X-ray-to-optical flux ratios.

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X-ray spectra of sources in the 13HXMM–Newton/Chandra deep field

Cited by 34 publications

References 60 publications

The X-ray spectral properties of the AGN population in theXMM-Newtonbright serendipitous survey

The X-ray spectral properties of the AGN population in theXMM-Newtonbright serendipitous survey

The XMM-NewtonWide Angle Survey (XWAS): the X-ray spectrum of type-1 AGN

TheXMM-NewtonWide Angle Survey (XWAS)

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