Back to Volume
Paper: Probing the Evolution of AGN
Volume: 290, Active Galactic Nuclei: from Central Engine to Host Galaxy
Page: 611
Authors: Hoyle, F.; Vogeley, M.; vanden Berk, D.; Voges, W.; Fan, X.
Abstract: Recent optical studies of AGN have revealed the unexpected result that the amplitude of clustering does not evolve with redshift. The likely dependence of AGN clustering on the host halo mass and heterogeneity in the events that trigger the efficiency of feeding the central engine imply that the observed clustering may strongly vary with wavelength and other selection criteria. However, progress on these issues has been limited by the small size of redshift samples of AGN selected at other than optical wavelengths. Here we describe a unique project that has recently obtained NASA funding that will combine X-ray, UV, IR and optically selected data to study the clustering of AGN. We will analyze samples of AGN detected in the X-ray band by the ROSAT, UV imaging and spectroscopy from the GALEX mission, IR imaging from SIRTF, together with results of the 2dF and SDSS QSO surveys. The spatial clustering of AGN reflects both the distribution of matter fluctuations in the universe and the complex non-linear astrophysics of black hole formation and feeding. The evolution of the AGN clustering amplitude is a crucial constraint on models of AGN, as this depends on the mass of the host halo at the epoch when the central engine shines brightly in the selection waveband. Precise measurements of AGN clustering as a function of parameters measured in multi wavebands will allow us to address key questions such as what are the lifetimes and environments of AGN? Are fluctuations in the X-ray background consistent with an AGN population? What is the power spectrum of mass, as traced by AGN, and does this evolve with redshift?
Back to Volume