Dust Emission from a Parsec-Scale Structure in the Seyfert 1 Nucleus of NGC 4151
Abstract
We report mid-infrared interferometric measurements (based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, programme number 081.B-0092(A)) with ~10 mas resolution, which resolve the warm (T = 285+25 -50 K) thermal emission at the center of NGC 4151. Using pairs of Very Large Telescope 8.2 m telescopes with the Mid-infrared interferometric instrument and by comparing the data to a Gaussian model, we determined the diameter of the dust emission region, albeit only along one position angle, to be (2.0 ± 0.4) pc (FWHM). This is the first size and temperature estimate for the nuclear warm dust distribution in a Seyfert 1 galaxy. The parameters found are comparable to those in Seyfert 2 galaxies, thus providing direct support for the unified model. Using simple analytic temperature distributions, we find that the mid-infrared emission is probably not the smooth continuation of the hot nuclear source that is marginally resolved with K-band interferometry. We also detected weak excess emission around 10.5 μm in our shorter baseline observation, possibly indicating that silicate emission is extended to the parsec scale.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2009
- DOI:
- 10.1088/0004-637X/705/1/L53
- arXiv:
- arXiv:0909.5191
- Bibcode:
- 2009ApJ...705L..53B
- Keywords:
-
- galaxies: active;
- galaxies: Seyfert;
- techniques: high angular resolution;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 5 pages, 4 figures, accepted for publication in The Astrophysical Journal Letters