Imaging Large-Scale Structure in the X-Ray Sky

Yang, Yujin; Mushotzky, R. F.; Barger, A. J.; Cowie, L. L.; Sanders, D. B.; Steffen, A. T.

doi:10.1086/374372

Cited by 67 publications

(105 citation statements)

References 30 publications

(42 reference statements)

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“…Puccetti et al (2006) are also in agreement with us (θ 0 = 12.8 ± 7.8 arcsec) within their large uncertainties. For a canonical slope of 0.8, Yang et al (2003) found θ 0 = 40±11 arcsec, much larger than ours (θ 0 = 5.9±0.3 arcsec) with a significance of ∼4σ. Such a strong clustering is somewhat surprising and it is much higher than any other reported angular clustering analysis in this band using a fixed canonical slope (although it is roughly consistent with the result of Basilakos et al 2004 for a fixed γ − 1 = 0.8).…”

Section: Resultscontrasting

confidence: 80%

“…(2003) found a ∼2σ clustering signal in Chandra observations of the Lockman Hole North-West region with θ 0 = 4 ± 2 arcsec. The samples used by Yang et al (2003) and Miyaji et al (2007) reach limiting fluxes one order of magnitude deeper than that of our sample. Therefore, their very low correlation lengths compared with ours could be explained in terms of a dependence of the clustering strength on the flux limit of the sample involved (see Sect.…”

Section: Resultsmentioning

confidence: 66%

“…Summary of the fits in different flux-limited subsamples. (Yang et al 2003), COSMOS (Miyaji et al 2007), XMM-2dF (Basilakos et al 2004(Basilakos et al , 2005, ELAIS-S1 (Puccetti et al 2006), XMM-LSS (Gandhi et al 2006) and AXIS ). In Fig.…”

Section: Dependence On the Flux Limitmentioning

confidence: 99%

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High-precision multi-band measurements of the angular clustering of X-ray sources

Ebrero¹,

Mateos²,

Stewart³

et al. 2009

A&A

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Aims. We aim to study the large-scale structure of an extragalactic serendipitous X-ray survey with unprecedented accuracy thanks to the large statistics involved, and provide insight into the environment of AGN at the epochs when their space density declines (z ∼ 1−2). Methods. In this paper we present the two-point angular correlation function of the X-ray source population of 1063 XMM-Newton observations at high Galactic latitudes, comprising up to ∼30 000 sources over a sky area of ∼125.5 deg 2 , in three energy bands: 0.5-2 (soft), 2-10 (hard), and 4.5-10 (ultrahard) keV. This is the largest survey of serendipitous X-ray sources ever used for clustering analysis. Results. We have measured the angular clustering of our survey and find significant positive clustering signals in the soft and hard bands (∼10σ and ∼5σ, respectively), and a marginal clustering detection in the ultrahard band (<1σ). We find dependency of the clustering strength on the flux limit and no significant differences in the clustering properties between sources with high hardness ratios (and therefore likely to be obscured AGN) and those with low hardness ratios. We deprojected the angular clustering parameters via Limber's equation to compute their typical spatial lengths. From that we have inferred that AGN at redshifts of ∼1 are embedded in dark matter haloes with typical masses of log M DMH 12.60 ± 0.34 h −1 M and lifetimes of t AGN = 3.1−4.5 × 10 8 yr. Conclusions. Our results show that obscured and unobscured objects share similar clustering properties and therefore they both reside in similar environments, in agreement with the unified model of AGN. The short AGN lifetimes derived suggest that AGN activity might be a transient phase that can be experienced several times by a large fraction of galaxies throughout their lives.

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Section: Resultscontrasting

confidence: 80%

Section: Resultsmentioning

confidence: 66%

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High-precision multi-band measurements of the angular clustering of X-ray sources

Ebrero¹,

Mateos²,

Stewart³

et al. 2009

A&A

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show abstract

“…Solid line: reflection+leaky absorber model, see text for details. Cappelluti et al 2005Cappelluti et al , 2007Yang et al 2003, and references therein). These fluctuations have been explained by superposition of Poissonian noise and fluctuations introduced by the clustering of the sources.…”

Section: Discussionmentioning

confidence: 99%

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

Brunner¹,

Cappelluti²,

Hasinger³

et al. 2007

A&A

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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“…However, the only current survey with a very high level of spectroscopic identifications is the Chandra Large Area Synoptic X-ray Survey (CLASXS), which consists of nine overlapped Chandra ACIS-I pointings in the Lockman Hole Northwest field covering ∼0.4 square degrees to X-ray flux limits of f 2−8 keV ≈3 × 10 −15 and f 0.5−2 keV ≈5 × 10 −16 ergs cm −2 s −1 . Yang et al (2003) found that the full range of cosmic variance seen in the earlier, individual Chandra pointings was represented in the number counts of the nine CLASXS pointings. They found the clustering in both the hard and soft X-ray bands to be significant, though, interestingly, the X-ray sources detected only in the hard band appeared to be substantially more clustered.…”

Section: Chandra X-ray Datamentioning

confidence: 89%