The typecasting of active galactic nuclei: Mrk 590 no longer fits the role

K. D. Denney, G. De Rosa, K. Croxall, A. Gupta, M. C. Bentz, M. M. Fausnaugh, C. J. Grier, P. Martini, S. Mathur, B. M. Peterson, R. W. Pogge, B. J. Shappee

Research output: Contribution to journalArticlepeer-review

119 Scopus citations

Abstract

We present multiwavelength observations that trace more than 40 yr in the life of the active galactic nucleus (AGN) in Mrk 590, traditionally known as a classic Seyfert 1 galaxy. From spectra recently obtained from Hubble Space Telescope, Chandra, and the Large Binocular Telescope, we find that the activity in the nucleus of Mrk 590 has diminished so significantly that the continuum luminosity is a factor of 100 lower than the peak luminosity probed by our long-baseline observations. Furthermore, the broad emission lines, once prominent in the UV/optical spectrum, have all but disappeared. Since AGN type is defined by the presence of broad emission lines in the optical spectrum, our observations demonstrate that Mrk 590 has now become a "changing-look" AGN. If classified by recent optical spectra, Mrk 590 would be a Seyfert ∼1.9-2, where the only broad emission line still visible in the optical spectrum is a weak component of Hα. As an additional consequence of this change, we have definitively detected UV narrow-line components in a Type 1 AGN, allowing an analysis of these emission-line components with high-resolution COS spectra. These observations challenge the historical paradigm that AGN type is only a consequence of the line-of-sight viewing angle toward the nucleus in the presence of a geometrically flattened, obscuring medium (i.e., the torus). Our data instead suggest that the current state of Mrk 590 is a consequence of the change in luminosity, which implies the black hole accretion rate has significantly decreased.

Original languageEnglish (US)
Article number134
JournalAstrophysical Journal
Volume796
Issue number2
DOIs
StatePublished - Dec 1 2014
Externally publishedYes

Keywords

  • galaxies: Seyfert
  • galaxies: active
  • galaxies: individual (Mrk 590)
  • galaxies: nuclei
  • quasars: emission lines

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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