The XXL Survey: XXXII. Spatial clustering of the XXL-S AGN

Plionis, M.; Koutoulidis, L.; Koulouridis, E.; Moscardini, L.; Lidman, C.; Pierre, M.; Adami, C.; Chiappetti, L.; Faccioli, L.; Fotopoulou, S.; Pacaud, F.; Paltani, S.

Abstract

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.

Citation

Plionis, M., Koutoulidis, L., Koulouridis, E., Moscardini, L., Lidman, C., Pierre, M., …Paltani, S. (2018). The XXL Survey: XXXII. Spatial clustering of the XXL-S AGN. Astronomy & Astrophysics, 620, Article A17. https://doi.org/10.1051/0004-6361/201832970

• Journal Article Type: Article
• Acceptance Date: Apr 9, 2018
• Online Publication Date: Nov 20, 2018
• Publication Date: Nov 20, 2018
• Deposit Date: Dec 6, 2018
• Publicly Available Date: Dec 6, 2018
• Journal: Astronomy and astrophysics.
• Print ISSN: 0004-6361
• Electronic ISSN: 1432-0746
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 620
• Article Number: A17
• DOI: https://doi.org/10.1051/0004-6361/201832970
• Public URL: https://durham-repository.worktribe.com/output/1341565