We review the variety of Active Galactic Nuclei (AGN) classes (so-called\AGN zoo") and classification schemes of galaxies by activity types based on their optical emission-line spectrum, as well as other parameters and other than optical wave-length ranges. A historical overview of discoveries of various types of active galaxies is given, including Seyfert galaxies, radio galaxies, QSOs, BL Lacertae objects, Star-bursts, LINERs, etc. Various kinds of AGN diagnostics are discussed. All known AGN types and subtypes are presented and described to have a homogeneous classification scheme based on the optical emission-line spectra and in many cases, also other parameters. Problems connected with accurate classifications and open questions related to AGN and their classes are discussed and summarized.
Mickaelian, A. M. (2015). AGN Zoo and Classi cations of Active Galaxies. Iranian Journal of Astronomy and Astrophysics, 2(1), 1-38. doi: 10.22128/ijaa.2015.15
MLA
Areg M. Mickaelian. "AGN Zoo and Classi cations of Active Galaxies", Iranian Journal of Astronomy and Astrophysics, 2, 1, 2015, 1-38. doi: 10.22128/ijaa.2015.15
HARVARD
Mickaelian, A. M. (2015). 'AGN Zoo and Classi cations of Active Galaxies', Iranian Journal of Astronomy and Astrophysics, 2(1), pp. 1-38. doi: 10.22128/ijaa.2015.15
VANCOUVER
Mickaelian, A. M. AGN Zoo and Classi cations of Active Galaxies. Iranian Journal of Astronomy and Astrophysics, 2015; 2(1): 1-38. doi: 10.22128/ijaa.2015.15
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