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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 709947.0, MPI für Astronomie / Publikationen_mpia
ALMA reveals the feeding of the Seyfert 1 nucleus in NGC 1566
Authors:Combes, F.; García-Burillo, S.; Casasola, V.; Hunt, L. K.; Krips, M.; Baker, A. J.; Boone, F.; Eckart, A.; Marquez, I.; Neri, R.; Schinnerer, E.; Tacconi, L. J.
Date of Publication (YYYY-MM-DD):2014
Title of Journal:Astronomy and Astrophysics
Start Page:id. A97 (11 pp)
End Page:(11 pp)
Review Status:Internal review
Audience:Experts Only
Abstract / Description:We report ALMA observations of CO(3-2) emission in the Seyfert 1 galaxy NGC 1566, at a spatial resolution of 25 pc. Our aim is to investigate the morphology and dynamics of the gas inside the central kpc, and to probe nuclear fueling and feedback phenomena. NGC 1566 has a nuclear bar of 1.7 kpc radius and a conspicuous grand design spiral starting from this radius. The ALMA field of view, of diameter 0.9 kpc, lies well inside the nuclear bar and reveals a molecular trailing spiral structure from 50 to 300 pc in size, which is contributing to fuel the nucleus, according to its negative gravity torques. The spiral starts with a large pitch angle from the center and then winds up in a pseudo-ring at the inner Lindblad resonance (ILR) of the nuclear bar. This is the first time that a trailing spiral structure is clearly seen driving the gas inwards inside the ILR ring of the nuclear bar. This phenomenon shows that the massive central black hole has a significant dynamical influence on the gas, triggering its fueling. The gaseous spiral is well correlated with the dusty spiral seen through extinction in HST images, and also with a spiral feature emitting 0.87 mm continuum. This continuum emission must come essentially from cold dust heated by the interstellar radiation field. The HCN(4-3) and HCO+(4-3) lines were simultaneously mapped and detected in the nuclear spiral. The HCO+(4-3) line is 3 times stronger than the HCN(4-3), as expected when star formation excitation dominates over active galactic nucleus (AGN) heating. The CO(3-2)/HCO+(4-3) integrated intensity ratio is ~100. The molecular gas is in remarkably regular rotation, with only slight non-circular motions at the periphery of the nuclear spiral arms. These perturbations are quite small, and no outflow nor AGN feedback is detected. Based on observations carried out with ALMA in cycle 0.
Free Keywords:galaxies: active; galaxies: individual: NGC 1566; galaxies: ISM; galaxies: kinematics and dynamics; galaxies: nuclei; galaxies: spiral
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-6361 %R 10.1051/0004-6361/201423433 [ID No:1]
URL:http://cdsads.u-strasbg.fr/abs/2014A%26A...565A..9... [ID No:2]
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