Dissecting the active galactic nucleus in Circinus -- I. Peculiar mid-IR morphology explained by a dusty hollow cone
arXiv:1708.07838 · doi:10.1093/mnras/stx2227
Abstract
Recent high angular resolution observations resolved for the first time the mid-infrared (MIR) structure of nearby active galactic nuclei (AGN). Surprisingly, they revealed that a major fraction of their MIR emission comes from the polar regions. This is at odds with the expectation based on AGN unification, which postulates a dusty torus in the equatorial region. The nearby, archetypical AGN in the Circinus galaxy offers one of the best opportunities to study the MIR emission in greater detail. New, high quality MIR images obtained with the upgraded VISIR instrument at the Very Large Telescope show that the previously detected bar-like structure extends up to at least 40 pc on both sides of the nucleus along the edges of the ionization cone. Motivated by observations across a wide wavelength range and on different spatial scales, we propose a phenomenological dust emission model for the AGN in the Circinus galaxy consisting of a compact dusty disk and a large-scale dusty cone shell, illuminated by a tilted accretion disk with an anisotropic emission pattern. Undertaking detailed radiative transfer simulations, we demonstrate that such a model is able to explain the peculiar MIR morphology and account for the entire IR spectral energy distribution. Our results call for caution when attributing dust emission of unresolved sources entirely to the torus and warrant further investigation of the MIR emission in the polar regions of AGN.
Accepted to MNRAS. Version 2: typos corrected
References in corpus (15)
- SKIRT: an Advanced Dust Radiative Transfer Code with a User-Friendly Architecture
- Resolving the complex structure of the dust torus in the active nucleus of the Circinus galaxy
- The innermost region of AGN tori: implications from the HST/NICMOS Type 1 point sources and near-IR reverberation
- Resolving the obscuring torus in NGC 1068 with the power of infrared interferometry: Revealing the inner funnel of dust
- The 2-79 keV X-ray Spectrum of the Circinus Galaxy with NuSTAR, XMM-Newton and Chandra: a Fully Compton-Thick AGN
- Far-infrared and dust properties of present-day galaxies in the EAGLE simulations
- Multi-phase Nature of a Radiation-Driven Fountain with Nuclear Starburst in a Low-mass Active Galactic Nucleus
- VLTI/VINCI observations of the nucleus of NGC 1068 using the adaptive optics system MACAO
- Non-conservative evolution in Algols: where is the matter?
- Geometrically thick obscuration by radiation-driven outflow from magnetized tori of active galactic nuclei
- Silicate Dust in Active Galactic Nuclei
- Possible evidence for a common radial structure in nearby AGN tori
- Gravitational microlensing of AGN dusty tori
- Modelling ripples in Orion with coupled dust dynamics and radiative transfer
- The Spatial Variation of the 3micron Dust Features in Circinus