Multiwavelength monitoring of the dwarf seyfert 1 galaxy NGC 4395. I. A reverberation-based measurement of the black hole mass

Bradley M. Peterson, Misty C. Bentz, Louis Benoit Desroches, Alexei V. Filippenko, Luis C. Ho, Shai Kaspi, Ari Laor, Dan Maoz, Edward C. Moran, Richard W. Pogge, Alice C. Quillen

Research output: Contribution to journalArticlepeer-review

Abstract

A reverberation-mapping program on NGC 4395, the least luminous known Seyfert 1 galaxy, undertaken with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope yields a measurement of the mass of the central black hole MBH = (3.6 ± 1.1) × 105 M . The observations consist of two visits of five orbits each, in 2004 April and July. During each of these visits, the UV continuum varied by at least 10% (rms), and only C IV λ1549 showed corresponding variations large enough to reliably determine the emission-line lag, which was measured to be of order 1 hr for both visits. The size of the C IV-emitting region is about a factor of 3 smaller than expected if the slope of the broad-line region radius-luminosity relationship is identical to that for the Hβ emission line. NGC 4395 is under-luminous even for its small black hole mass; the Eddington ratio of ∼ 1.2 × 10-3 is lower than that of any other active galactic nucleus for which a black hole mass measurement has been made by emission-line reverberation.

Original languageEnglish
Pages (from-to)799-808
Number of pages10
JournalAstrophysical Journal
Volume632
Issue number2 I
DOIs
StatePublished - 20 Oct 2005

Keywords

  • Galaxies: active
  • Galaxies: nuclei
  • Galaxies: seyfert
  • Quasars: emission lines
  • Ultraviolet: galaxies

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