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The Properties of “Dwarf” Seyfert Nuclei in Nearby Galaxies

  • Alexei V. Filippenko
  • Wallace L. W. Sargent
Part of the Astrophysics and Space Science Library book series (ASSL, volume 121)

Abstract

Accurate knowledge of the luminosity function of active galactic nuclei over a wide range of absolute magnitudes is a prerequisite to understanding their structure and evolution. Here we describe preliminary results from a large survey of bright, nearby galaxies which is designed to quantify the faint end of the luminosity function. Many high-quality spectra are shown to emphasize the great variety of physical conditions in the nuclei and to illustrate the methods used in a detailed analysis of the data. The characteristics of Seyfert galaxies are detected in a surprisingly large number of objects, although at much fainter levels than usually reported for classical AGNs. In particular, broad Hα emission is visible in at least 10% of the nuclei, and the relative intensities of narrow lines are often indicative of photoionization by a nonstellar continuum. A very wide range of densities is found in the narrow-line regions of certain low-ionization nuclei, just as in many QSOs and Seyfert 1 galaxies. These results suggest that intrinsically faint (“dwarf”), but nevertheless active, nuclei are much more common than previously believed, and that they may have evolved from luminous quasars.

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Copyright information

© Springer Science+Business Media Dordrecht 1986

Authors and Affiliations

  • Alexei V. Filippenko
    • 1
  • Wallace L. W. Sargent
    • 2
  1. 1.Department of AstronomyUniversity of CaliforniaBerkeleyUSA
  2. 2.Palomar ObservatoryCalifornia Institute of TechnologyPasadenaUSA

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