Towards a Better Understanding of Active Galactic Nuclei

Abstract

Active Galactic Nuclei (AGN) are ideal sources for multi-wavelength studies as their emission can cover almost 20 orders of magnitude in frequency from the radio to the gamma-ray band. After reviewing their basic properties, I will assess how well we know the multifrequency spectra of AGN as a class. I will then briefly illustrate how currently available and forthcoming sky surveys will help in addressing some of the open questions of AGN studies. Finally, an analysis of the problem of the missing Type 2 QSO will exemplify the dangers of monochromatic sky surveys for AGN.

9 pages, 2 figures, LaTeX file, uses crckapb.sty and psfig.tex. Invited Review at IAU Symposium 179 "New Horizons from Multiwavelength Sky Surveys", to be published in the proceedings. TeX and postscript files also available at http://itovf2.roma2.infn.it/padovani/multi.html