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Thick turbulent gas disks with magnetocentrifugal winds in active galactic nuclei - Model infrared emission and optical polarization

Thick turbulent gas disks with magnetocentrifugal winds in active galactic nuclei - Model infrared emission and optical polarization
Thick turbulent gas disks with magnetocentrifugal winds in active galactic nuclei - Model infrared emission and optical polarization
(Abridged) Infrared high-resolution imaging and interferometry have shown that the dust distribution is frequently elongated along the polar direction of an AGN. To explain these findings, we developed a model scenario for the inner ~30 pc of an AGN. We assume a rotating thick gas disk between about one and ten parsec. External gas accretion adds mass and injects energy via gas compression into this gas disk and drives turbulence. Our disks are assumed to be strongly magnetized via equipartition between the turbulent gas pressure and the energy density of the magnetic field. In a second step, we built three dimensional density cubes based on the analytical model, illuminated them with a central source, and made radiative transfer calculations. In a third step, we calculated MIR visibility amplitudes and compared them to available interferometric observations. We show that magneto centrifugal winds starting from a thin and thick gas disk are viable in active galaxy centers. Once the wind is launched, it is responsible for the transport of angular momentum and the gas disk can become thin. The outflow scenario can account for the elongated dust structures, outer edges of the thin maser disks, and molecular outflows observed in local AGN. The models reproduce the observed terminal wind velocities, the scatter of the MIR/intrinsic X-ray correlation, and point source fractions. An application of the model to the Circinus Galaxy and NGC1068 shows that the IR SED, available MIR interferometric observations,and optical polarization can be reproduced in a satisfactory way,provided that (i) a puff-up at the inner edge of the thin disk is present and (ii) a local screen with an optical depth of tau_V 20 inform of a local gas filament and/or a warp of the thick disk hide a significant fraction of both nuclei.
Astrophysics - Astrophysics of Galaxies
0004-6361
Vollmer, B.
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Schartmann, M.
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Burtscher, L.
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Marin, F.
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Hoenig, S.
be0bb8bc-bdac-4442-8edc-f735834f3917
Davies, R.
de556a64-6bea-46ee-a71d-c58bf7647f3d
Goosmann, R.
b35e0bb7-d474-4b0a-a827-245f8e1da724
Vollmer, B.
c51691d5-7be9-4362-a1e3-20cf227cb50e
Schartmann, M.
3faff300-98a4-43ea-b6cf-3ff2e0022c27
Burtscher, L.
62c9bc4d-a775-4512-995b-fd84a206b4e8
Marin, F.
5431b356-3386-42d5-8d4f-570a4e2ce271
Hoenig, S.
be0bb8bc-bdac-4442-8edc-f735834f3917
Davies, R.
de556a64-6bea-46ee-a71d-c58bf7647f3d
Goosmann, R.
b35e0bb7-d474-4b0a-a827-245f8e1da724

Vollmer, B., Schartmann, M., Burtscher, L., Marin, F., Hoenig, S., Davies, R. and Goosmann, R. (2018) Thick turbulent gas disks with magnetocentrifugal winds in active galactic nuclei - Model infrared emission and optical polarization. Astronomy & Astrophysics, 615. (doi:10.1051/0004-6361/201731133).

Record type: Article

Abstract

(Abridged) Infrared high-resolution imaging and interferometry have shown that the dust distribution is frequently elongated along the polar direction of an AGN. To explain these findings, we developed a model scenario for the inner ~30 pc of an AGN. We assume a rotating thick gas disk between about one and ten parsec. External gas accretion adds mass and injects energy via gas compression into this gas disk and drives turbulence. Our disks are assumed to be strongly magnetized via equipartition between the turbulent gas pressure and the energy density of the magnetic field. In a second step, we built three dimensional density cubes based on the analytical model, illuminated them with a central source, and made radiative transfer calculations. In a third step, we calculated MIR visibility amplitudes and compared them to available interferometric observations. We show that magneto centrifugal winds starting from a thin and thick gas disk are viable in active galaxy centers. Once the wind is launched, it is responsible for the transport of angular momentum and the gas disk can become thin. The outflow scenario can account for the elongated dust structures, outer edges of the thin maser disks, and molecular outflows observed in local AGN. The models reproduce the observed terminal wind velocities, the scatter of the MIR/intrinsic X-ray correlation, and point source fractions. An application of the model to the Circinus Galaxy and NGC1068 shows that the IR SED, available MIR interferometric observations,and optical polarization can be reproduced in a satisfactory way,provided that (i) a puff-up at the inner edge of the thin disk is present and (ii) a local screen with an optical depth of tau_V 20 inform of a local gas filament and/or a warp of the thick disk hide a significant fraction of both nuclei.

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1803.06182 - Accepted Manuscript
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Accepted/In Press date: 18 March 2018
e-pub ahead of print date: 3 August 2018
Keywords: Astrophysics - Astrophysics of Galaxies

Identifiers

Local EPrints ID: 421569
URI: http://eprints.soton.ac.uk/id/eprint/421569
ISSN: 0004-6361
PURE UUID: 74ee964e-9d2e-4da4-8e43-ec15c15c9ed2

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Date deposited: 15 Jun 2018 16:30
Last modified: 30 Jan 2020 05:05

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