A new analysis of the nucleus of NGC 1068 with MIDI observations

Anne Poncelet (1, 2, 3) , Guy Perrin (2, 3) , Hélène Sol (1)

1 LUTH (UMR_8102) - Laboratoire Univers et Théories
2 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
3 Pôle Astronomie du LESIA

We present a new analysis of the first mid-infrared N-band long-baseline interferometric observations of an extragalactic source: the nucleus of the Seyfert 2 galaxy NGC 1068, obtained with MIDI (Mid-InfrareD Interferometer), the mid-infrared beamcombiner at the European Southern Observatory (ESO) Very Large Telescope Interferometer (VLTI). The resolution of lambda/B ˜ 10 mas allows us to study the compact central core of the galaxy between 8 and 13 mum. Both visibility measurements and MIDI spectrum are well reproduced by a simple radiative transfer model with two concentric spherical components. The derived angular sizes and temperatures are ~35 and 83 mas, and ~361 K and 226 K for these two components respectively. Other evidence strongly supports such low temperatures. This modeling also provides the variation of optical depth as a function of wavelength for the extended component across the N-band suggesting the presence of amorphous silicate grains. This shows that MIDI has carried out the first direct observations of the distribution of dust around the central engine.

Domaines: Astrophysique [astro-ph]; Planète et Univers [physics]

Anne Poncelet, Guy Perrin, Hélène Sol. A new analysis of the nucleus of NGC 1068 with MIDI observations. Astronomy and Astrophysics - A&A, 2006, 450, pp.483-494. ⟨10.1051/0004-6361:20053608⟩. ⟨hal-03785781⟩