Resolving the nucleus of Centaurus A at mid-IR wavelengths

Abstract

We have observed Centaurus A with the MID-infrared Interferometric instrument (MIDI) at the Very Large Telescope Interferometer (VLTI) at resolutions of 7 - 15 mas (at 12.5 micron) and filled gaps in the (u,v) coverage in comparison to earlier measurements. We are now able to describe the nuclear emission in terms of geometric components and derive their parameters by fitting models to the interferometric data. With simple geometrical models, the best fit is achieved for an elongated disk with flat intensity profile with diameter 76 +/- 9 mas x 35 +/- 2 mas (1.41 +/- 0.17 pc x 0.65 +/- 0.03 pc) whose major axis is oriented at a position angle (PA) of 10.1 +/- 2.2 degrees east of north. A point source contributes 47 +/- 11 % of the nuclear emission at 12.5 micron. There is also evidence that neither such a uniform nor a Gaussian disk are good fits to the data. This indicates that we are resolving more complicated small-scale structure in AGNs with MIDI, as has been seen in Seyfert galaxies previously observed with MIDI. The PA and inferred inclination i = 62.6 +2.1/-2.6 degrees of the dust emission are compared with observations of gas and dust at larger scales.

Accepted for the PASA special issue on Centaurus A

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• The subarcsecond mid-infrared view of local active galactic nuclei: I. The N- and Q-band imaging atlas
• Testing the Unification Model for AGN in the Infrared: are the obscuring tori of Type 1 and 2 Seyferts different?
• Mapping the radial structure of AGN tori
• Revealing the large nuclear dust structures in NGC 1068 with MIDI/VLTI
• Time-resolved infrared emission from radiation-driven central obscuring structures in Active Galactic Nuclei
• The radio continuum structure of Centaurus A at 1.4 GHz
• VLTI/AMBER observations of the Seyfert nucleus of NGC 3783
• On the size-luminosity relation of AGN dust tori in the mid-infrared
• Disentangling the Circumnuclear Environs of Centaurus A: III. An Inner Molecular Ring, Nuclear Shocks and the CO to warm H2 interface
• Twelve and a Half Years of Observations of Centaurus A with RXTE
• A Compact Jet at the Infrared Heart of the Prototypical Low-Luminosity AGN in NGC 1052
• Dust in the central parsecs of unobscured AGN: more challenges to the torus
• Infrared Interferometry and AGNs: Parsec-scale Disks and Dusty Outflows
• Science with MATISSE