Reverberation Measurements of the Inner Radius of the Dust Torus in 17 Seyfert Galaxies
Abstract
I present the results of a dust reverberation survey for 17 nearby Seyfert 1 galaxies in MAGNUM project, which provides the largest homogeneous collection of the innermost radii of dust tori. As a result of a cross- correlation function analysis and an alternative posterior probability distribution method, 49 measurements were obtained through the time lags between V and K band flux variations. The time lags we found to strongly correlated to the optical luminosity in the range of -16 to -22 mag in M_V with the regression line log(Delta t) = (-2.11 - 0.2)M_V , assuming (Delta t) prop. to L^{0.5} as theoretically expected. The intrinsic scatter of 0.13 dex can be counted partly by the variation of both internal extinction and delayed response of the time- lag variations against the optical flux variations. Any systematic correlation of the scatter was not found along the Seyfert type nor the Eddington ratio. The correlation by dust reverberation was compared with that by the near-infrared interferometry and that by the reverberation mapping of broad Balmer emission lines. The interferometric radii were found to be systematically larger than the dust reverberation radii by a factor of two, which could be interpreted as the difference between the flux-weighted and the response-weighted radii. The reverberation radii of the broad lines were systematically smaller by a factor of four or five, which strongly supports the unified scheme on Seyfert type of active galactic nuclei. The radius-luminosity correlations for the hard X-ray (14-195 keV) and the [Oiv]25.89 micron emission-line luminosities are also presented.
- Publication:
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TORUS2015: The AGN Unification Scheme After 30 Years
- Pub Date:
- September 2015
- Bibcode:
- 2015toru.conf..O08K
- Keywords:
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- Active Galactic Nuclei