From the Circumnuclear Disk in the Galactic Center to thick, obscuring tori of AGNs -- Modelling the molecular emission of a parsec-scale torus as found in NGC1068

Abstract

The accretion rates needed to fuel the central black hole in a galaxy can be achieved via viscous torques in thick disks and rings, which can be resolved by millimetre interferometry within the inner ~20pc of the active galaxy NGC1068 at comparable scales and sensitivity to single dish observations of the Circumnuclear Disk (CND) in the Galactic Center. To interpret observations of these regions and determine the physical properties of their gas distribution, we present a modelling effort that includes (i) a simple dynamical simulations involving partially inelastic collisions between disk gas clouds, (ii) an analytical model of a turbulent clumpy gas disk calibrated by the dynamical model and observations, (iii) local turbulent and cosmic ray gas heating and cooling via H2O, H2, and CO emission, and (iv) determination of the molecular abundances. We also consider photodissociation regions (PDR) where gas is directly illuminated by the central engine. We compare the resulting model datacubes of the CO, HCN, HCO+, and CS brightness temperatures to available observations. In both cases the kinematics can be explained by one or two clouds colliding with a pre-existing ring, in a prograde sense for the CND and retrograde for NGC1068. And, with only dense disk clouds, the line fluxes can be reproduced to within a factor of about two. To avoid self-absorption of the intercloud medium, turbulent heating at the largest scales, comparable to the disk height, has to be decreased by a factor of 50-200. Our models indicate that turbulent mechanical energy input is the dominant gas heating mechanism within the thick gas disks. In N1068, while the bulk of the AGN X-ray radiation is absorbed in a layer of Compton-thick gas inside the dust sublimation radius, the optical/UV radiation may enhance the molecular line emission from photodissociation regions by ~50% at the inner edge of the gas ring.

36 pages, 32 figures, accepted for publication in A&A

References in corpus (27)

• A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
• The Statistics of Supersonic Isothermal Turbulence
• Multi-Scale CLEAN deconvolution of radio synthesis images
• A Close Look at Star Formation around Active Galactic Nuclei
• The 2014 KIDA network for interstellar chemistry
• Diagnostics of irradiated dense gas in galaxy nuclei. II. A grid of XDR and PDR models
• Modeling Complex Organic Molecules in dense regions: Eley-Rideal and complex induced reaction
• ALMA images the many faces of the NGC1068 torus and its surroundings
• Kinematics of the Narrow-Line Region in the Seyfert 2 Galaxy NGC 1068: Dynamical Effects of the Radio Jet
• The Galaxy Activity, Torus and Outflow Survey (GATOS) I. ALMA images of dusty molecular tori in Seyfert galaxies
• Vibrationally Excited HCN in the Luminous Infrared Galaxy NGC 4418
• High-Velocity Bipolar Molecular Emission from an AGN Torus
• An image of the dust sublimation region in the nucleus of NGC 1068
• Counter-Rotation and High Velocity Outflow in the Parsec-Scale Molecular Torus of NGC 1068
• Cold CO in circumstellar disks: On the effects of photodesorption and vertical mixing
• Modelling the sulphur chemistry evolution in Orion KL
• A new look at sulphur chemistry in hot cores and corinos
• Starbursts and torus evolution in AGN
• ALMA 0.02"-resolution observations reveal HCN-abundance-enhanced counter-rotating and outflowing dense molecular gas at the NGC 1068 nucleus
• A two-stage outflow in NGC 1068
• The Circumnuclear Disk Revealed by ALMA. I. Dense Clouds and Tides in the Galactic Center
• Counter-Rotating Accretion Discs
• A Chandra and ALMA Study of X-ray-irradiated Gas in the Central ~100 pc of the Circinus Galaxy
• Turbulent energy dissipation and intermittency in ambipolar diffusion magnetohydrodynamics
• Kelvin-Helmholtz Instability of Counter-Rotating Discs
• Velocity-inverted three-dimensional distribution of the gas clouds in the Type 2 AGN NGC1068