The Chandra COSMOS Legacy Survey: Clustering of X-Ray-selected AGNs at 2.9 ≤ z ≤ 5.5 Using Photometric Redshift Probability Distribution Functions

Journal
Date Issued
2016
Author(s)
•
Civano, F.
•
Finoguenov, A.
•
•
Shankar, F.
•
Zamorani, G.
•
Hasinger, G.
•
Salvato, M.
•
Miyaji, T.
•
•
Cappelluti, N.
•
Brusa, M.
•
Suh, H.
•
•
Trakhtenbrot, B.
•
Griffiths, R.
•
Vignali, C.
•
Schawinski, K.
•
Karim, A.
DOI
Abstract
We present the measurement of the projected and redshift-space two-point correlation function (2pcf) of the new catalog of Chandra COSMOS-Legacy active galactic nucleus (AGN) at 2.9 ≤ z ≤ 5.5 (< {L}{bol}> ∼ 1046 erg s-1) using the generalized clustering estimator based on phot-z probability distribution functions in addition to any available spec-z. We model the projected 2pcf, estimated using π max = 200 h-1 Mpc with the two-halo term and we derive a bias at z ∼ 3.4 equal to b = {6.6}-0.55+0.60, which corresponds to a typical mass of the hosting halos of log M h = {12.83}-0.11+0.12 h-1 M ☉. A similar bias is derived using the redshift-space 2pcf, modeled including the typical phot-z error σ z = 0.052 of our sample at z ≥ 2.9. Once we integrate the projected 2pcf up to π max = 200 h-1 Mpc, the bias of XMM and Chandra COSMOS at z = 2.8 used in Allevato et al. is consistent with our results at higher redshifts. The results suggest only a slight increase of the bias factor of COSMOS AGNs at z ≳ 3 with the typical hosting halo mass of moderate-luminosity AGNs almost constant with redshift and equal to log M h = {12.92}-0.18+0.13 at z = 2.8 and log M h = {12.83}-0.11+0.12 at z ∼ 3.4, respectively. The observed redshift evolution of the bias of COSMOS AGNs implies that moderate-luminosity AGNs still inhabit group-sized halos at z ≳ 3, but slightly less massive than observed in different independent studies using X-ray AGNs at z ≤ 2.
Volume
832
Issue
1
Start page
70
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2016ApJ...832...70A
Rights
open.access
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