English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The present paper analyses the quasar clustering using the two-pointcorrelation function (2pCF) and the largest existing sample of photometricallyselected quasars: the SDSS NBCKDE catalogue (from the SDSS DR6). A newtechnique of random catalogue generation was developed for this purpose, thatallows to take into account the original homogeneity of the survey withoutknowledge of its imaging mask. When averaged over photometrical redshifts0.8<z_phot<2.2 the 2pCF of photometrically selected quasars is found to beapproximated well with the power law w(\theta)=(\theta/\theta_0)^{-\alpha} with\theta_0=4".5+/-1".4, \alpha=0.94+/-0.06 over the range 1'<\theta<40'. Itagrees well with previous results by Myers et al. (2006,2007), obtained forsamples of NBCKDE quasars with similar mean z_phot, but averaged over broaderz_phot range. The parameters of the deprojected 2pCF averaged over the samez_phot range and modelled with a power law \xi(r)=(r/r_0)^{-\gamma}, arer_0=7.81^{+1.18}_{-1.16} Mpc/h, \gamma=1.94+/-0.06, which are in perfectagreement with previous results from spectroscopic surveys. We confirm theevidence for an increase of the clustering amplitude with z, and find noevidence for luminosity dependence of the quasar clustering. The latter isconsistent with the models of the quasar formation, in which bright and faintquasars are assumed to be similar sources, hosted by dark matter halos ofsimilar masses, but observed at different stages of their evolution. Comparisonof our results with studies of the X-ray selected AGNs with similar z showsthat the clustering amplitude of optically selected quasars is similar to thatof X-ray selected quasars, but lower than that of samples of all X-ray selectedAGNs. As the samples of all X-ray selected AGNs contain AGNs of both types, ourresult serves as an evidence for different types of AGNs to reside in differentenvironments.

Angular and spatial clustering of photometrically classified quasar candidates from SDSS NBCKDE