摘要：Aims.We study the spatial clustering of 632 (1130) XMM-COSMOS active galactic nuclei (AGNs) with known spectroscopic or photometric redshifts in the rangez = [0.1–2.5] in order to measure the AGN bias and estimate the typical mass of the hosting dark matter (DM) halo as a function of AGN host galaxy properties.Methods.We created AGN subsamples in terms of stellar mass,M*, and specific black hole accretion rate,LX/M*, to study how AGN environment depends on these quantities. Further, we derived theM*−Mhalorelation for our sample of XMM-COSMOS AGNs and compared it to results in literature for normal non-active galaxies. We measured the projected two-point correlation functionwp(rp) using both the classic and the generalized clustering estimator, based on photometric redshifts, as probability distribution functions in addition to any available spectroscopic redshifts. We measured the large-scale (rp≳ 1h−1Mpc) linear biasbby comparing the clustering signal to that expected of the underlying DM distribution. The bias was then related to the typical mass of the hosting haloMhaloof our AGN subsamples. SinceM*andLX/M*are correlated, we matched the distribution in terms of one quantity and we split the distribution in the other.Results.For the full spectroscopic AGN sample, we measured a typical DM halo mass of log (Mhalo/h−1M⊙) = 12.79−0.43+0.26, similar to galaxy group environments and in line with previous studies for moderate-luminosity X-ray selected AGN. We find no significant dependence on specific accretion rateLX/M*, with log (Mhalo/h−1M⊙) = 13.06−0.38+0.23and log (Mhalo/h−1M⊙) = 12.97−1.26+0.39for low and highLX/M*subsamples, respectively. We also find no difference in the hosting halos in terms ofM*with log (Mhalo/h−1M⊙) = 12.93−0.62+0.31(low) and log (Mhalo/h−1M⊙) = 12.90−0.62+0.30(high). By comparing theM*−Mhalorelation derived for XMM-COSMOS AGN subsamples with what is expected for normal non-active galaxies by abundance matching and clustering results, we find that the typical DM halo mass of our highM*AGN subsample is similar to that of non-active galaxies. However, AGNs in our lowM*subsample are found in more massive halos than non-active galaxies. By excluding AGNs in galaxy groups from the clustering analysis, we find evidence that the result for lowM*may be due to larger fraction of AGNs as satellites in massive halos.
关键词：endark mattergalaxies: activegalaxies: evolutionlarge-scale structure of Universequasars: generalsurveys
