Volume 620, December 2018
The XXL Survey: second series
|Number of page(s)||7|
|Section||Cosmology (including clusters of galaxies)|
|Published online||20 November 2018|
The XXL Survey
XXXII. Spatial clustering of the XXL-S AGN★
National Observatory of Athens, Lofos Nymfon, Thession,
2 Physics Department, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
3 AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France
4 Dipartimento di Fisica e Astronomia, Alma Mater Studiorum Università di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
5 INAF - Osservatorio di Astrofisica e Scienza dello Spazio, via Gobetti 93/3, 40129 Bologna, Italy
6 INFN, Sezione di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy
7 Australian Astronomical Observatory, PO Box 915, North Ryde NSW 1670, Australia
8 LAM, OAMP, Université Aix-Marseille, CNRS, Pôle de l’Étoile, Site de Chãteau Gombert, 38 rue Frédéric Joliot-Curie, 13388 Marseille 13 Cedex, France
9 INAF - IASF - Milano, Via Bassini 15, 20133 Milano, Italy
10 Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham, DH1 3LE, UK
11 Argelander Institut fuer Astronomie, Universitaet Bonn, Auf dem Huegel 71, 53121 Bonn, Germany
12 Department of Astronomy, University of Geneva, ch. d’Ecogia 16, 1290 Versoix, Switzerland
Accepted: 9 April 2018
The XMM-XXL Survey spans two fields of 25 deg2 each observed for more than 6 Ms with XMM, which provided a sample of tens of thousands of point sources with a flux limit of ~2.2 × 10−15 and ~1.4 × 10−14 erg s−1 cm2, corresponding to 50% of the area curve, in the soft band (0.5–2 keV) and hard band (2–10 keV), respectively. In this paper we present the spatial clustering properties of ~3100 and ~1900 X-ray active galactic nuclei (AGNs) in the soft and hard bands, respectively, which have been spectroscopically observed with the AAOmega facility. This sample is 90% redshift complete down to an optical magnitude limit of r ≲ 21.8. The sources span the redshift interval 0 < z < 5.2, although in the current analysis we limit our samples to z ≤ 3, with corresponding sample median values of z̅ ≃ 0.96 and 0.79 for the soft band and hard band, respectively. We employ the projected two-point correlation function to infer the spatial clustering and find a correlation length r0 = 7.0(±0.34) and 6.42(±0.42) h−1 Mpc, respectively, for the soft- and hard-band detected sources with a slope for both cases of γ = 1.44(±0.1). The power-law clustering was detected within comoving separations of 1 and ~25 h−1 Mpc. These results, as well as those derived in two separate redshift ranges, provide bias factors of the corresponding AGN host dark matter halos that are consistent with a halo mass of log10[Mh∕(h−1M⊙)] = 13.04 ± 0.06, confirming the results of most recent studies based on smaller X-ray AGN samples.
Key words: galaxies: active / surveys
© ESO 2018
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.