skip to main content

Title: BROAD Hβ EMISSION-LINE VARIABILITY IN A SAMPLE OF 102 LOCAL ACTIVE GALAXIES

A sample of 102 local (0.02 ≤ z ≤ 0.1) Seyfert galaxies with black hole masses M{sub BH} > 10{sup 7}M{sub ⊙} was selected from the Sloan Digital Sky Survey (SDSS) and observed using the Keck 10 m telescope to study the scaling relations between M{sub BH} and host galaxy properties. We study profile changes of the broad Hβ emission line within the three to nine year time frame between the two sets of spectra. The variability of the broad Hβ emission line is of particular interest, not only because it is used to estimate M{sub BH}, but also because its strength and width are used to classify Seyfert galaxies into different types. At least some form of broad-line variability (in either width or flux) is observed in the majority (∼66%) of the objects, resulting in a Seyfert-type change for ∼38% of the objects, likely driven by variable accretion and/or obscuration. The broad Hβ line virtually disappears in 3/102 (∼3%) extreme cases. We discuss potential causes for these changing look active galactic nuclei. While similar dramatic transitions have previously been reported in the literature, either on a case-by-case basis or in larger samples focusing on quasars at higher redshifts, our study providesmore » statistical information on the frequency of Hβ line variability in a sample of low-redshift Seyfert galaxies.« less
Authors:
; ; ;  [1] ;  [2] ; ;  [3] ;  [4] ;  [5] ;  [6]
  1. Physics Department, California Polytechnic State University, San Luis Obispo CA 93407 (United States)
  2. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121, Bonn (Germany)
  3. Department of Physics, University of California, Los Angeles, CA 90095 (United States)
  4. Department of Physics and Physical Science, University of Nebraska Kearney, Kearney, NE 68849 (United States)
  5. Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)
  6. Korea Astronomy and Space Science Institute, Daejeon, 34055 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22518505
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 821; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; BLACK HOLES; EMISSION SPECTRA; GALAXY NUCLEI; HYDROGEN; MASS; QUASARS; RED SHIFT; SEYFERT GALAXIES; STAR ACCRETION; TELESCOPES