Multi-frequency databases for AGN investigation - Results and
  perspectives
  Active Galactic Nuclei (AGNs) are characterized by emission of radiation over
more than 10 orders of magnitude in frequency. Therefore, the execution of
extensive surveys of the sky, with different types of detectors, is providing
the attractive possibility to identify and to investigate the properties of
AGNs on very large statistical samples. Thanks to the large spectroscopic
surveys that allow detailed investigation of many of these sources, we have the
opportunity to place new constraints on the nature and evolution of AGNs and to
investigate their relations with the host systems. In this contribution we
present the results that can be obtained by using a new interactive catalogue
that we developed to investigate the range of AGN spectral energy distributions
(SEDs). We present simple SED models based on data collected in the catalogue
and discuss their relations with optical spectra obtained by follow up
observations. We compare our findings with the expectations based on the AGN
Unification Model, and we discuss the perspectives of multi-wavelength
approaches to address AGN related processes such as black hole accretion and
acceleration of relativistic jets.
