Bibcode
DOI
Prieto, M. Almudena; Meisenheimer, K.; Marco, Olivier; Reunanen, Juha; Contini, Marcella; Clenet, Y.; Davies, R. I.; Gratadour, D.; Henning, Th.; Klaas, U.; Kotilainen, J.; Leinert, Ch.; Lutz, D.; Rouan, D.; Thatte, N.
Bibliographical reference
The Astrophysical Journal, Volume 614, Issue 1, pp. 135-141.
Advertised on:
10
2004
Journal
Citations
51
Refereed citations
45
Description
VLT J- to M'-band adaptive optics observations of the Circinus galaxy on
parsec scales resolve a central bright Ks-band source with a
FWHM size of 1.9+/-0.6 pc. This source is only visible at wavelengths
longward of 1.6 μm and coincides in position with the peak of the [Si
VII] 2.48 μm coronal line emission. With respect to the peak of the
central optical emission, the source is shifted by ~0.15" (2.8 pc) to
the southeast. Indeed, the Ks-band source defines the vertex
of a fairly collimated beam that extends for ~10 pc and is seen in both
continuum light shortward of 1.6 μm and in Hα line emission.
The source also lies at the center of a ~19 pc size [Si VII] ionization
bicone. Identifying this source as the nucleus of Circinus, its size is
compatible with a putative parsec-scale torus. Its spectral energy
distribution, characterized by a prominent narrow peak, is compatible
with a dust temperature of 300 K. Hotter dust within a 1 pc radius of
the center is not detected. The active galactic nucleus (AGN) luminosity
required to heat this dust is in the range of X-ray luminosities that
have been measured toward the central source. This in turn supports the
existence of highly obscuring material, with column densities of
1024 cm-2, that must be located within 1 pc of the
core.