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

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Violette Impellizzeri, CM  ORCID logo  https://orcid.org/0000-0003-4561-1713
Baum, SA 
Davies, R 

Abstract

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. 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 consistent with the nearly edge-on, geometrically thin water megamaser disk in Keplerian rotation around a central mass of 1.66×107M⊙. 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.

Description

Keywords

galaxies: active, Interstellar medium, quasars: supermassive black holes, Radio interferometry, Seyfert galaxies

Journal Title

Astrophysical Journal Letters

Conference Name

Journal ISSN

2041-8205
2041-8213

Volume Title

884

Publisher

American Astronomical Society

Rights

All rights reserved
Sponsorship
European Research Council (695671)
Science and Technology Facilities Council (ST/M001172/1)
ERC grant 695671 'QUENCH'