Black hole feeding and star formation in NGC 1808
Artikel i vetenskaplig tidskrift, 2021

We report on Atacama Large Millimeter Array (ALMA) observations of CO(3-2) emission in the Seyfert2/starburst galaxy NGC1808, at a spatial resolution of 4 pc. Our aim is to investigate the morphology and dynamics of the gas inside the central 0.5 kpc and to probe the nuclear feeding and feedback phenomena. We discovered a nuclear spiral of radius 100 = 45 pc. Within it, we found a decoupled circumnuclear disk or molecular torus of a radius of 0:1300 = 6 pc. The HCN(4-3) and HCO+(4-3) and CS(7-6) dense gas line tracers were simultaneously mapped and detected in the nuclear spiral and they present the same misalignment in the molecular torus. At the nucleus, the HCN/HCO+ and HCN/CS ratios indicate the presence of an active galactic nucleus (AGN). The molecular gas shows regular rotation, within a radius of 400 pc, except for the misaligned disk inside the nuclear spiral arms. The computations of the torques exerted on the gas by the barred stellar potential reveal that the gas within a radius of 100 pc is feeding the nucleus on a timescale of five rotations or on an average timescale of 60 Myr. Some non-circular motions are observed towards the center, corresponding to the nuclear spiral arms. We cannot rule out that small extra kinematic perturbations could be interpreted as a weak outflow attributed to AGN feedback. The molecular outflow detected at 250 pc in the NE direction is likely due to supernovae feedback and it is connected to the kpc-scale superwind.

Galaxies: kinematics and dynamics

Galaxies: nuclei

Galaxies: ISM

Galaxies: starburst

Galaxies: individual: NGC 1808

Galaxies: active


A. Audibert

Observatoire de Paris

Instituto de Astrofísica de Canarias

National Observatory of Athens

Universidad de la Laguna

F. Combes

Collège de France

Observatoire de Paris

S. G. Burillo

Observatorio Astronómico Nacional (OAN)

L. K. Hunt

Osservatorio Astrofisico di Arcetri

A. Eckart

Universität zu Köln

Susanne Aalto

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

V. Casasola

Istituto di Radioastronomia

F. Boone

Institut de Recherche en Astrophysique et Planétologie (IRAP)

M. Krips

Institut de Radioastronomie Millimétrique (IRAM)

Serena Viti

University College London (UCL)

Universiteit Leiden

Sebastien Muller

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium

K. M. Dasyra

National Observatory of Athens

University of Athens

P. van der Werf

Universiteit Leiden

S. Martin

European Southern Observatory Santiago

Atacama Large Millimeter-submillimeter Array (ALMA)

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 656 A60


Astronomi, astrofysik och kosmologi

Atom- och molekylfysik och optik

Fusion, plasma och rymdfysik



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