First Results from the X‐Ray and Optical Survey of the<i>Chandra</i>Deep Field South

Giacconi, R.; Rosati, P.; Tozzi, P.; Nonino, M.; Hasinger, G.; Norman, C.; Bergeron, J.; Borgani, S.; Gilli, R.; Gilmozzi, R.; Zheng, Wei

doi:10.1086/320222

Cited by 470 publications

(606 citation statements)

References 36 publications

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“…The average hardening of faint sources agrees with the shape of the CXB in approximately the same energy range (Marshall et al 1980), as already found at lower energies (e.g., Mushotzky et al 2000;Brandt et al 2001;Giacconi et al 2001). There is one notable outlier with a negative Γ valuethe CT thick source in the COSMOS field reported by C15 (cosmos330 in Table 2).…”

Section: Nustar Spectral Analysissupporting

confidence: 83%

The NuSTAR Extragalactic Surveys: X-Ray Spectroscopic Analysis of the Bright Hard-band Selected Sample

Zappacosta

Comastri

Civano

et al. 2018

ApJ

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We discuss the spectral analysis of a sample of 63 active galactic nuclei (AGN) detected above a limiting flux of S 8 24 keV 7 10 14 =´-( -) erg s cm 1 2 --in the multi-tiered NuSTAR extragalactic survey program. The sources span a redshift range z 0 2.1 = -(median z 0.58 á ñ = ). The spectral analysis is performed over the broad 0.5-24keV energy range, combining NuSTAR with Chandra and/or XMM-Newton data and employing empirical and physically motivated models. This constitutes the largest sample of AGN selected at 10 keV > to be homogeneously spectrally analyzed at these flux levels. We study the distribution of spectral parameters such as photon index, column density (N H ), reflection parameter (R), and 10-40keV luminosity (L X ). Heavily obscured ( N log cm 23AGN constitute ∼25% (15-17 sources) and ∼2-3% (1-2 sources) of the sample, respectively. The observed N H distribution agrees fairly well with predictions of cosmic X-ray background population-synthesis models (CXBPSM). We estimate the intrinsic fraction of AGN as a function of N H , accounting for the bias against obscured AGN in a flux-selected sample. The fraction of CT AGN relative to N log cm 20 24AGN is poorly constrained, formally in the range 2-56% (90% upper limit of 66%). We derived a fraction ( f abs ) of obscured AGN ( N log cm 22 24as a function of L X in agreement with CXBPSM and previous z 1 < X-ray determinations. Furthermore, f abs at z 0.1 0.5 = -and L log erg s 43.6 44.3agrees with observational measurements/trends obtained over larger redshift intervals. We report a significant anti-correlation of R with L X (confirmed by our companion paper on stacked spectra) with considerable scatter around the median R values.

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Section: Nustar Spectral Analysissupporting

confidence: 83%

The NuSTAR Extragalactic Surveys: X-Ray Spectroscopic Analysis of the Bright Hard-band Selected Sample

Zappacosta

Comastri

Civano

et al. 2018

ApJ

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“…The CXB is the superposition of resolved and unresolved emission coming from distant X-ray sources, such as AGNs (Giacconi et al 2001). Although this component is generated by sources with different redshift and spectral distributions, it can be modelled by a power law with a photon index Γ = 1.42 (e.g., Lumb et al 2002).…”

Section: Introductionmentioning

confidence: 99%

ChandraACIS-I particle background: an analytical model

Bartalucci

Mazzotta

Bourdin

et al. 2014

A&A

101

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Aims. Imaging and spectroscopy of X-ray extended sources require a proper characterisation of a spatially unresolved background signal. This background includes sky and instrumental components, each of which are characterised by its proper spatial and spectral behaviour. While the X-ray sky background has been extensively studied in previous work, here we analyse and model the instrumental background of the ACIS-I detector on board the Chandra X-ray observatory in very faint mode. Methods. Caused by interaction of highly energetic particles with the detector, the ACIS-I instrumental background is spectrally characterised by the superimposition of several fluorescence emission lines onto a continuum. To isolate its flux from any sky component, we fitted an analytical model of the continuum to observations performed in very faint mode with the detector in the stowed position shielded from the sky, and gathered over the eight-year period starting in 2001. The remaining emission lines were fitted to blank-sky observations of the same period. We found 11 emission lines. Analysing the spatial variation of the amplitude, energy and width of these lines has further allowed us to infer that three lines of these are presumably due to an energy correction artefact produced in the frame store. Results. We provide an analytical model that predicts the instrumental background with a precision of 2% in the continuum and 5% in the lines. We use this model to measure the flux of the unresolved cosmic X-ray background in the Chandra deep field south. We obtain a flux of 10.

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“…the sensitivity of the deepest surveys performed by the Chandra observatory (i.e. the Chandra deep field North and South, Bauer et al 2004;Giacconi et al 2001), the larger collecting area of XMM-Newton offers the possibility to perform a spectral analysis of a large fraction of the detected sources down to the confusion limit, opening up a powerful window into the cosmological evolution of the X-ray universe.…”

Section: Introductionmentioning

confidence: 99%

XMM-Newtonobservations of the Lockman Hole: X-ray source catalogue and number counts

Brunner¹,

Cappelluti²,

Hasinger³

et al. 2007

A&A

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130

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Context. The Lockman Hole field represents the sky area of lowest Galactic line-of-sight column density N H = 5.7 × 10 19 cm −2 . It was observed by the XMM-Newton X-ray observatory in 18 pointings for a total of 1.16 Ms (raw EPIC pn observing time) constituting the deepest XMM-Newton exposure so far. After the removal of time intervals with high particle background, the final effective exposure was 637 ks. Aims. We present a catalogue of the X-ray sources detected in the central 0.196 deg 2 of the field and discuss the derived number counts and X-ray colours. Methods. The analysis was performed using the XMM-SAS data analysis package version 6.0. The detection sensitivity and fraction of spurious detections was calibrated using Monte Carlo simulations. Results. In the 0.5−2.0 keV band, a sensitivity limit (defined as the faintest detectable source) of 1.9 × 10 −16 erg cm −2 s −1 was reached. The 2.0−10.0 keV band and 5.0−10.0 keV band sensitivity limits were 9×10 −16 erg cm −2 s −1 and 1.8×10 −15 erg cm −2 s −1 , respectively. A total of 409 sources above a detection likelihood of 10 (3.9 sigma) were found within a radius of 15 off the field centre, of which 340, 266, and 98 sources were detected in the soft, hard, and very hard bands, respectively. The number counts in each energy band are in close agreement with results from previous surveys and with the synthesis models of the X-ray background. Six percent of the Compton-thick source candidates have been selected from the X-ray colour-colour diagram. This fraction is consistent with the most recent predictions of X-ray background population synthesis models at our flux limits. We also estimated, for the first time, the log N − log S relation for Compton-thick AGN.

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First Results from the X‐Ray and Optical Survey of theChandraDeep Field South

Cited by 470 publications

References 36 publications

The NuSTAR Extragalactic Surveys: X-Ray Spectroscopic Analysis of the Bright Hard-band Selected Sample

The NuSTAR Extragalactic Surveys: X-Ray Spectroscopic Analysis of the Bright Hard-band Selected Sample

ChandraACIS-I particle background: an analytical model

XMM-Newtonobservations of the Lockman Hole: X-ray source catalogue and number counts

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