Geometrically thick obscuration by radiation-driven outflow from magnetized tori of active galactic nuclei

Abstract

Near-Eddington radiation from active galactic nuclei (AGNs) has significant dynamical influence on the surrounding dusty gas, plausibly furnishing AGNs with geometrically thick obscuration. We investigate this paradigm with radiative magnetohydrodynamics simulations. The simulations solve the magnetohydrodynamics equations simultaneously with the infrared (IR) and ultraviolet (UV) radiative transfer (RT) equations; no approximate closure is used for RT. We find that our torus, when given a suitable sub-Keplerian angular momentum profile, spontaneously evolves toward a state in which its opening angle, density distribution, and flow pattern change only slowly. This "steady" state lasts for as long as there is gas resupply toward the inner edge. The torus is best described as a mid-plane inflow and a high-latitude outflow. The outflow is launched from the torus inner edge by UV radiation and expands in solid angle as it ascends; IR radiation continues to drive the wide-angle outflow outside the central hole. The dusty outflow obscures the central source in soft X-rays, the IR, and the UV over three quarters of solid angle, and each decade in column density covers roughly equal solid angle around the central source; these obscuration properties are similar to what observations imply.

23 pages, 12 figures, published in ApJ

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Cited by in corpus (9)

• ALMA images the many faces of the NGC1068 torus and its surroundings
• Dissecting the active galactic nucleus in Circinus -- I. Peculiar mid-IR morphology explained by a dusty hollow cone
• Dissecting the active galactic nucleus in Circinus -- II. A thin dusty disc and a polar outflow on parsec scales
• Circumnuclear Multi-phase Gas in Circinus Galaxy I: Non-LTE calculations of CO lines
• Parsec-scale Dusty Winds in Active Galactic Nuclei: Evidence for Radiation Pressure Driving
• Obscuring fraction of active galactic nuclei implied by supernova and radiative feedbacks
• X-ray signatures of the polar dusty gas in AGN
• The Nuclear Filaments inside the Circumnuclear Disk in the Central 0.5 pc of the Galactic center
• Magneto Rotational Instability in Magnetized AGN Tori