The Asiago-ESO/RASS QSO Survey. III. Clustering analysis and its theoretical interpretation
Abstract
This is the third paper of a series describing the Asiago-ESO/RASS QSO survey (AERQS), a project aimed at the construction of an all-sky statistically well-defined sample of relatively bright QSOs (B<15) at z<0.3. We present here the clustering analysis of the full spectroscopically identified database (392 AGN). The clustering signal at 0.02<z<0.22 is detected at a 3-4 sigma level and its amplitude is measured to be r_0=8.6\pm 2.0 h^{-1} Mpc (in a Lambda CDM model). The comparison with other classes of objects shows that low-redshift QSOs are clustered in a similar way to Radio Galaxies, EROs and early-type galaxies in general, although with a marginally smaller amplitude. The comparison with recent results from the 2QZ shows that the correlation function of QSOs is constant in redshift or marginally increasing toward low redshift. We discuss this behavior with physically motivated models, deriving interesting constraints on the typical mass of the dark matter halos hosting QSOs, M_{DMH}= 10^{12.5} h^{-1} solar masses. Finally, we use the clustering data to infer the physical properties of local AGN, obtaining M_{BH}= 6.7 10^7 h^{-1} solar masses for the mass of the active black holes, tau_{AGN}= 4.4 10^6 yr for their life-time and eta=0.4 for their efficiency (always for a Lambda CDM model).Keywords
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