Luminosity-dependent X-ray active galactic nucleus clustering?

We have analyzed the angular clustering of X-ray-selected active galactic nuclei (AGNs) in different flux-limited subsamples of the Chandra Deep Field North (CDF-N) and South (CDF-S) surveys. We find a strong dependence of the clustering strength on the subsample flux limit, a fact that explains most of the disparate clustering results of different XMM and Chandra surveys. Using Limber's equation, we find that the inverted CDF-N and CDF-S spatial clustering lengths are consistent with direct spatial clustering measures found in the literature, while at higher flux limits the clustering length increases considerably; for example, at f(x,limit) similar to 10(-15) ergs s(-1) cm(-2), we obtain r(0) similar or equal to 17 +/- 5 and 18 +/- 3 h(-1) Mpc for the CDF-N and CDF- S, respectively. We show that the observed flux limit clustering trend hints toward an X-ray luminosity dependent clustering of X-ray selected, z similar to 1 AGNs.