XMM-Newton observation of the Lockman Hole

Mainieri, V.; Bergeron, J.; Hasinger, G.; Lehmann, I.; Rosati, P.; Schmidt, Maarten; Szokoly, G.; Ceca, R. Della

doi:10.1051/0004-6361:20020991

Cited by 202 publications

(334 citation statements)

References 29 publications

(84 reference statements)

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“…This is in agreement with the previous study of Panessa & Bassani (2002) who estimated that the fraction of unobscured Seyfert 2 (Sy2) varies between 10 to 30%. These results are consistent with what was found by Mainieri et al (2002) (30%) and Caccianiga et al (2004) (12%). However, Risaliti et al (1999) found an even smaller fraction of only 4%.…”

Section: Introductionsupporting

confidence: 94%

A new sample of X-ray selected narrow emission-line galaxies

Pons

Watson

2016

A&A

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A sample of X-ray and optically selected narrow emission-line galaxies (769 sources) from the 3XMM catalogue cross-correlated with SDSS (DR9) catalogue has been studied. Narrow-emission line active galactic nuclei (AGN; type-2) have been selected on the basis of their emission line ratios and/or X-ray luminosity. We have looked for X-ray unobscured type-2 AGN. As X-ray spectra were not available for our whole sample, we have checked the reliability of using the X-ray hardness ratio (HR) as a probe of the level of obscuration and we found a very good agreement with full spectral fitting results, with only 2% of the sources with apparently unobscured HR turning out to have an obscured spectrum. Despite the fact that type-2 AGN are supposed to be absorbed based on the Unified Model, about 60% of them show no sign or very low level of X-ray obscuration. After subtraction of contaminants to the sample, that is Narrow-Line Seyfert 1 and Compton-thick AGN, the fraction of unobscured Sy2 drops to 47%. For these sources, we were able to rule out dust reddening and variability for most of them as an explanation of the absence of optical broad emission-lines. The main explanations remaining are the dilution of weak/very broad emission-lines by the host galaxy and the intrinsic absence of the broad-line region (BLR) due to low accretion rates (i.e. True Sy2). However, the number of True Sy2 strongly depends on the method used to verify the intrinsic lack of broad lines. Indeed using the optical continuum luminosity to predict the BLR properties gives a much larger fraction of True Sy2 (about 90% of the unobscured Sy2 sample) than the use of the X-ray 2 keV luminosity (about 20%). Nevertheless the number of AGN we securely detected as True Sy2 is at least three times larger that the previously confirmed number of True Sy2.

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Section: Introductionsupporting

confidence: 94%

A new sample of X-ray selected narrow emission-line galaxies

Pons

Watson

2016

A&A

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“…This distribution confirm the already remarked disagreement between the prediction from X-ray background population synthesis models ( [5]), with a maximum around z ∼ 1.5, and the recent observations. Such a discrepancy was already noted for the 100 ksec observation of the Lockman Hole with XMM-Newton [8] and for the 1 Msec Chandra survey of the CDFS [10].…”

Section: X-ray Samplementioning

confidence: 60%

“…In particular, the EPIC cameras have a larger field-of-view than ACIS allowing for the detection of a number of new diffuse sources just outside the Chandra field-of-view. The EPIC instruments have unprecedent high sensitivity in the hard X-ray band, and in the [5][6][7][8][9][10] keV band our dataset is comparable to the 1Ms Chandra image. Analysis of the Lockman Hole (LH; [7]) has also confirmed the idea that Xray spectroscopy of a large number of sources is very powerful with XMM-Newton.…”

Section: X-ray Observationsmentioning

confidence: 68%

“…These plots show the differences between the observed values (when we assume that z = 0 if we do not know redshift, and that the N H obtained is only a lower limit) and the proper values of N H in the source rest-frame (e.g. [8]). …”

Section: Photon Index and Column Densitymentioning

confidence: 96%

“…The best-fit slope of the stacked spectra for [1][2][3][4][5][6][7][8] keV is 1.773 ± 0.031, 1.568 ± 0.024, 1.333 ± 0.041, and 1.178 ± 0.031, respectively.…”

Section: Subsamples Of the Sourcesmentioning

confidence: 99%

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

Streblyanska

Bergeron

Brunner

et al. 2004

Nuclear Physics B - Proceedings Supplements

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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 ×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, Γ = 2 ± 0.1. We present integrated spectrum for the most distant type-2 QSO with strong X-ray absorption and a clear soft excess; we obtained the best fit for these objects with two different 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 [14]. Our results shown a clear evolution of decrease of Γ with decreasing flux in the hard 2-10 keV band. However, we detect not only a regular increase of Γ 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.

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Chandra Deep Field South: the optically faint population

Mainieri¹,

Rosati²,

Nonino³

et al. 2003

Astron Nachr

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A not negligible fraction (similar to 15%) of X-ray sources detected in the 1 Msec observation of the Chandra Deep Field South (CDFS) are not detected down to Rsimilar or equal to 27. however they are registered in deep near-IR imaging. We use deep multicolor photometry from the VLT (FORS+ISAAC instruments), covering a broad wavelength range, to discuss the adequacy of such techniques for X-ray selected sources and to constrain the nature of this optically faint population

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XMM-Newton observation of the Lockman Hole

Cited by 202 publications

References 29 publications

A new sample of X-ray selected narrow emission-line galaxies

A new sample of X-ray selected narrow emission-line galaxies

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

Chandra Deep Field South: the optically faint population

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