A spectroscopic survey of X-ray-selected AGNs in the northern XMM-XXL field

Menzel, Marie-Luise; Merloni, A.; Georgakakis, A.; Salvato, M.; Aubourg, É.; Brandt, W. N.; Brusa, M.; Buchner, Johannes; Dwelly, T.; Nandra, K.; Pâris, Isabelle; Petitjean, P.; Schwope, A. D.

doi:10.1093/mnras/stv2749

Cited by 110 publications

(135 citation statements)

References 91 publications

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“…SDSS has been observing optically identified AGNs since its inception under the main large-scale structure surveys, special targeting programs, and as "mistakes" in other targeting classes. In addition, there were several BOSS ancillary programs focused on X-ray follow-up, including a highly complete program on the XMM-XXL north field (Menzel et al 2016). The SPIDERS SEQUELS program has added spectra of 274 ROSAT AGNs to the SDSS sample, identified on the basis of their SDSS colors only.…”

Section: Optical Spectra Of X-ray-identified Agnsmentioning

confidence: 99%

The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

Albareti

Prieto

Almeida

et al. 2017

ApJS

501

281

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Section: Optical Spectra Of X-ray-identified Agnsmentioning

confidence: 99%

The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

Albareti

Prieto

Almeida

et al. 2017

ApJS

501

281

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“…The 3XMM-DR4/SDSS overlapping area is ∼300 sq. deg, exceeding by several times the areas covered by known samples of distant X-ray quasars such as Champ (Kalfountzou et al, 2014) and XMM-XXL (north) (Menzel et al, 2016). The sample of Kalfountzou et al (2014) covers ≈33 sq.…”

Section: Introductionmentioning

confidence: 95%

“…Half of them have photometric redshifts only. The spectroscopic program of (Menzel et al, 2016) has revealed 61 X-ray objects at z spec > 3 in a 18 sq. deg subfield of XMM-XXL (north).…”

Section: Introductionmentioning

confidence: 99%

Catalog of 3 < z < 5.5 Quasar Candidates Selected among XMM-Newton Sources and Its Spectroscopic Verification

Хорунжев

Sazonov

Burenin

et al. 2017

Front. Astron. Space Sci.

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We have compiled a catalog of 903 quasar candidates (including known quasars) at 3 < z < 5.5 selected among X-ray sources from the XMM-Newton serendipitous survey (3XMM-DR4 catalog). We used photometric SDSS, 2MASS, and WISE data to select the objects. The surface number density of objects in our sample exceeds that in the SDSS spectroscopic quasar sample at the same redshifts by a factor of 1.5. We have performed spectroscopic observations of a subsample of new quasar candidates using a new low-and medium-resolution spectrograph at the 1.6-m AZT-33IK telescope (Mondy, Russia) and demonstrated that the purity of these candidates is about 65%. We have discovered one of the most distant (z = 5.08) X-ray selected quasars.

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“…For instance, if the actual counterpart is located in the wings of a much brighter nearby source it may not be detected. This effect probably accounts for the presence of a fraction of the stellar identifications in high Galactic latitude X-ray surveys, in particular those with a much higher F x /F opt flux ratios and harder X-ray spectra than normal for active coronae in which cases a faint AGN may be the correct identification (Watson 2012;Menzel et al 2016). One way to account for this effect and to limit the overestimation is to remove from the surface area Ω small areas around each source.…”

Section: Case Of Two Cataloguesmentioning

confidence: 99%

Probabilistic multi-catalogue positional cross-match

Pineau

Derriére

Motch

et al. 2017

A&A

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Context. Catalogue cross-correlation is essential to building large sets of multi-wavelength data, whether it be to study the properties of populations of astrophysical objects or to build reference catalogues (or timeseries) from survey observations. Nevertheless, resorting to automated processes with limited sets of information available on large numbers of sources detected at different epochs with various filters and instruments inevitably leads to spurious associations. We need both statistical criteria to select detections to be merged as unique sources, and statistical indicators helping in achieving compromises between completeness and reliability of selected associations. Aims. We lay the foundations of a statistical framework for multi-catalogue cross-correlation and cross-identification based on explicit simplified catalogue models. A proper identification process should rely on both astrometric and photometric data. Under some conditions, the astrometric part and the photometric part can be processed separately and merged a posteriori to provide a single global probability of identification. The present paper addresses almost exclusively the astrometrical part and specifies the proper probabilities to be merged with photometric likelihoods. Methods. To select matching candidates in n catalogues, we used the Chi (or, indifferently, the Chi-square) test with 2(n−1) degrees of freedom. We thus call this cross-match a χ -match. In order to use Bayes' formula, we considered exhaustive sets of hypotheses based on combinatorial analysis. The volume of the χ -test domain of acceptance -a 2(n − 1)-dimensional acceptance ellipsoid -is used to estimate the expected numbers of spurious associations. We derived priors for those numbers using a frequentist approach relying on simple geometrical considerations. Likelihoods are based on standard Rayleigh, χ and Poisson distributions that we normalized over the χ -test acceptance domain. We validated our theoretical results by generating and cross-matching synthetic catalogues. Results. The results we obtain do not depend on the order used to cross-correlate the catalogues. We applied the formalism described in the present paper to build the multi-wavelength catalogues used for the science cases of the Astronomical Resource Cross-matching for High Energy Studies (ARCHES) project. Our cross-matching engine is publicly available through a multi-purpose web interface. In a longer term, we plan to integrate this tool into the CDS XMatch Service.

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A spectroscopic survey of X-ray-selected AGNs in the northern XMM-XXL field

Cited by 110 publications

References 91 publications

The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

Catalog of 3 < z < 5.5 Quasar Candidates Selected among XMM-Newton Sources and Its Spectroscopic Verification

Probabilistic multi-catalogue positional cross-match

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