Towards a Better Understanding of Active Galactic Nuclei
Paolo Padovani
Original Version: `New Horizons from Multi-Wavelength Sky Surveys', B. McLean
et al. eds., p. 257.
Text copyright (c) 1998: Kluwer Academic Publishers
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.
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