Counter-rotation and High-velocity Outflow in the Parsec-scale Molecular Torus of NGC 1068

We present 1.4 pc resolution observations of 256 GHz nuclear radio continuum and HCN (J = 3 → 2) in the molecular torus of NGC 1068. The integrated radio continuum emission has a flat spectrum consistent with free-free emission and resolves into an X-shaped structure resembling an edge-brightened bi...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2019-10, Vol.884 (2), p.L28
Main Authors: Impellizzeri, C. M. Violette, Gallimore, Jack F., Baum, Stefi A., Elitzur, Moshe, Davies, Richard, Lutz, Dieter, Maiolino, Roberto, Marconi, Alessandro, Nikutta, Robert, O'Dea, Christopher P., Sani, Eleonora
Format: Article
Language:English
Subjects:
Absorption
Absorption spectra
Continuum radiation
Dwarf galaxies
Emission analysis
Emission lines
Galaxies
galaxies: active
Interstellar medium
Kinematics
Molecular gases
Morphology
Outflow
quasars: supermassive black holes
Radio interferometry
Rotating disks
Rotation
Seyfert galaxies
Spacecraft recovery
Toruses
Velocity
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Summary:We present 1.4 pc resolution observations of 256 GHz nuclear radio continuum and HCN (J = 3 → 2) in the molecular torus of NGC 1068. The integrated radio continuum emission has a flat spectrum consistent with free-free emission and resolves into an X-shaped structure resembling an edge-brightened bicone. HCN is detected in absorption against the continuum, and the absorption spectrum shows a pronounced blue wing that suggests a high-velocity molecular outflow with speeds reaching 450 km s−1. Analysis of the off-nucleus emission line kinematics and morphology reveals two nested, rotating disk components. The inner disk, inside r ∼ 1.2 pc, has kinematics that are consistent with the nearly edge-on, geometrically thin H2O megamaser disk in Keplerian rotation around a central mass of 1.66 × 107 M . The outer disk, which extends to ∼7 pc radius, counter-rotates relative to the inner disk. The rotation curve of the outer disk is consistent with rotation around the same central mass as the megamaser disk but in the opposite sense. The morphology of the molecular gas is asymmetric around the nuclear continuum source. We speculate that the outer disk formed from more recently introduced molecular gas falling out of the host galaxy or from a captured dwarf satellite galaxy. In NGC 1068, we find direct evidence that the molecular torus consists of counter-rotating and misaligned disks on parsec scales.
ISSN:2041-8205
2041-8213
DOI:10.3847/2041-8213/ab3c64