3D Radiation Hydrodynamics of a Dynamical Torus

Williamson, David; Hönig, S. F.; Venanzi, Marta

doi:10.3847/1538-4357/ab17d5

Cited by 31 publications

(38 citation statements)

References 55 publications

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“…Gas being swept up in a region that becomes self-obscured to the AGN radiation will have less momentum deposited, giving rise to a "failed wind". Such mass fallback has been seen in radiationhydrodynamic simulations (e.g Wada 2012; Williamson et al 2019), with observational evidence also found in low-velocity molecular outflow components of the Ciricnus galaxy . Gas presence in this fall-back region is transitional, probably of lower column density, and the lack of direct AGN radiation makes the region dark in the IR.…”

Section: The Dark Fall-back Regionsupporting

confidence: 61%

“…Pier & Krolik 1992;Fabian et al 2009;) and RHD simulations confirm it for both single dusty clumps as well as massive dusty molecular disks (e.g. Dorodnitsyn et al 2011;Schartmann et al 2011;Wada 2012;Namekata et al 2014;Namekata, & Umemura 2016;Chan & Krolik 2017;Williamson et al 2019). Such radiation pressure driving is most effective for regions with τ V ∼ 1.…”

Section: Physical Conditions Of the Dusty Molecular Gasmentioning

confidence: 86%

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Redefining the Torus: A Unifying View of AGNs in the Infrared and Submillimeter

Hönig

2019

ApJ

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134

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The advent of high-angular resolution IR and sub-mm interferometry allows for spatially-resolved observations of the parsec-scale environment of active galactic nuclei (AGN), commonly referred to as the "torus." While molecular lines show the presence of large, massive disks, the IR observations appear to be dominated by a strong polar component that has been interpreted as a dusty wind. This paper aims at using characteristics shared by AGN in each of the wavebands and a set of simple physical principles to form a unifying view of these seemingly contradictory observations: Dusty molecular gas flows in from galactic scales of ∼100 pc to the sub-parsec environment via a disk with small to moderate scale height. The hot, inner part of the disk puffs up due to IR radiation pressure and unbinds a large amount of the inflowing gas from the black hole's gravitational potential, providing the conditions to launch a wind driven by the radiation pressure from the AGN. The dusty wind feeds back mass into the galaxy at a rate of the order of ∼ 0.1 − 100 M /yr, depending on AGN luminosity and Eddington ratio. Angle-dependent obscuration as required by AGN unification is provided by a combination of disk, wind, and wind launching region.

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Section: The Dark Fall-back Regionsupporting

confidence: 61%

Section: Physical Conditions Of the Dusty Molecular Gasmentioning

confidence: 86%

Redefining the Torus: A Unifying View of AGNs in the Infrared and Submillimeter

Hönig

2019

ApJ

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134

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“…Proga et al 2000), with recent studies also involving dusty winds (e.g. Dorodnistyn et al 2016;Chan & Krolik 2017;Williamson et al 2019). The existence of dust within warm absorbers has been reported (e.g.…”

Section: Introductionmentioning

confidence: 81%

X-ray signatures of the polar dusty gas in AGN

Liu

Hönig

Ricci

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Recent mid-infrared interferometry observations of nearby active galactic nuclei (AGN) revealed that a significant part of the dust emission extends in the polar direction, rather than the equatorial torus/disk direction as expected by the traditional unification model. We study the X-ray signatures of this polar dusty gas with ray-tracing simulations. Different from those from the ionized gas, the scattered emission from the polar dusty gas produces self-absorption and neutral-like fluorescence lines, which are potentially a unique probe of the kinematics of the polar dusty gas. The anomalously small Fe Kα/Si Kα ratios of type II AGN observed previously can be naturally explained by the polar dusty gas, because the polar emission does not suffer from heavy absorption by the dense equatorial gas. The observed Si Kα lines of the Circinus galaxy and NGC 1068 show blue-shifts with respect to the systemic velocities of the host galaxies, consistent with an outflowing scenario of the Si Kα-emitting gas. The 2.5-3 keV image of the Circinus galaxy is elongated along the polar direction, consistent with an origin of the polar gas. These results show that the polar-gas-scattered X-ray emission of type II AGN is an ideal objective for future X-ray missions, such as Athena.

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“…Netzer 1987;Matthews et al 2017). In addition, the geometry of the flow in line-driven and dust-driven winds is also sensitive to the SED anisotropy Williamson et al 2019) and motivates further work involving multi-frequency radiation hy- drodynamics. Unlike M16, we do not have an emissivity profile with radius along the disc midplane, and all photon packets are launched from the central source.…”

Section: Kinematics Geometry and Input Sedmentioning

confidence: 94%

Stratified disc wind models for the AGN broad-line region: ultraviolet, optical, and X-ray properties

Matthews

Knigge

Higginbottom

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The origin, geometry and kinematics of the broad line region (BLR) gas in quasars and active galactic nuclei (AGN) are uncertain. We demonstrate that clumpy biconical disc winds illuminated by an AGN continuum can produce BLR-like spectra. We first use a simple toy model to illustrate that disc winds make quite good BLR candidates, because they are selfshielded flows and can cover a large portion of the ionizing flux-density (φ H -n H ) plane. We then conduct Monte Carlo radiative transfer and photoionization calculations, which fully account for self-shielding and multiple scattering in a non-spherical geometry. The emergent model spectra show broad emission lines with equivalent widths and line ratios comparable to those observed in AGN, provided that the wind has a volume filling factor of f V 0.1. Similar emission line spectra are produced for a variety of wind geometries (polar or equatorial) and for launch radii that differ by an order of magnitude. The line emission arises almost exclusively from plasma travelling below the escape velocity, implying that 'failed winds' are important BLR candidates. The behaviour of a line-emitting wind (and possibly any 'smooth flow' BLR model) is similar to that of the locally optimally-emitting cloud (LOC) model originally proposed by Baldwin et al (1995), except that the gradients in ionization state and temperature are large-scale and continuous, rather than within or between distinct clouds. Our models also produce UV absorption lines and X-ray absorption features, and the stratified ionization structure can partially explain the different classes of broad absorption line quasars.

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3D Radiation Hydrodynamics of a Dynamical Torus

Cited by 31 publications

References 55 publications

Redefining the Torus: A Unifying View of AGNs in the Infrared and Submillimeter

Redefining the Torus: A Unifying View of AGNs in the Infrared and Submillimeter

X-ray signatures of the polar dusty gas in AGN

Stratified disc wind models for the AGN broad-line region: ultraviolet, optical, and X-ray properties

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