VLTI/AMBER observations of the Seyfert nucleus of NGC 3783 ^⋆

G. Weigelt¹, K.-H. Hofmann¹, M. Kishimoto¹, S. Hönig², D. Schertl¹, A. Marconi^3,4, F. Millour⁵, R. Petrov⁵, D. Fraix-Burnet⁶, F. Malbet⁶, K. Tristram¹ and M. Vannier⁵

¹ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
e-mail: weigelt@mpifr.de
² UCSB Department of Physics, Broida Hall 2015H, Santa Barbara CA, USA
³ Dipartimento di Fisica e Astronomia, Universitá di Firenze, Largo Enrico Fermi 2, 510125 Firenze, Italy
⁴ INAF – Osservatorio Astrofisico di Arcetri, Largo Fermi 5, 50125 Firenze, Italy
⁵ Laboratoire Lagrange, UMR 7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d’Azur, 06300 Nice, France
⁶ Université Joseph Fourier (UJF) – Grenoble 1/CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, 38041 Grenoble, France

Received: 13 March 2012
Accepted: 6 April 2012

Abstract

Context. The putative tori surrounding the accretion disks of active galactic nuclei (AGNs) play a fundamental role in the unification scheme of AGNs. Infrared long-baseline interferometry allows us to study the inner dust distribution in AGNs with unprecedented spatial resolution over a wide infrared wavelength range.

Aims. Near- and mid-infrared interferometry is used to investigate the milli-arcsecond-scale dust distribution in the type 1.5 Seyfert nucleus of NGC 3783.

Methods. We observed NGC 3783 with the VLTI/AMBER instrument in the K-band and compared our observations with models.

Results. From the K-band observations, we derive a ring-fit torus radius of 0.74 ± 0.23 mas or 0.16 ± 0.05 pc. We compare this size with infrared interferometric observations of other AGNs and UV/optical-infrared reverberation measurements. For the interpretation of our observations, we simultaneously model our near- and mid-infrared visibilities and the spectral energy distribution (SED) with a temperature/density-gradient model including an additional inner hot 1400 K ring component.