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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 742747.0, MPI für Astronomie / Publikationen_mpia
Disentangling the circumnuclear environs of Centaurus A. III. An inner molecular ring, nuclear shocks, and the CO to warm H2 interface
Authors:Espada, D.; Matsushita, S.; Miura, R. E.; Israel, F. P.; Neumayer, N.; Martin, S.; Henkel, C.; Izumi, T.; Iono, D.; Aalto, S.; Ott, J.; Peck, A. B.; Quillen, A. C.; Kohno, K.
Date of Publication (YYYY-MM-DD):2017
Title of Journal:The Astrophysical Journal
Volume:843
Start Page:id. 136 (24 pp)
Audience:Not Specified
Abstract / Description:We present the distribution and kinematics of the molecular gas in the circumnuclear disk (CND; 400 pc × 200 pc) of Centaurus A with resolutions of ∼5 pc (0.″3) and shed light onto the mechanism feeding the active galactic nucleus (AGN) using CO(3–2), HCO+(4–3), HCN(4–3), and CO(6–5) observations obtained with ALMA. Multiple filaments or streamers of tens to a hundred parsec scale exist within the CND, which form a ring-like structure with an unprojected diameter of 9″ × 6″ (162 pc × 108 pc) and a position angle P.A. ≃ 155°. Inside the nuclear ring, there are two leading and straight filamentary structures with lengths of about 30–60 pc at P.A. ≃ 120° on opposite sides of the AGN, with a rotational symmetry of 180° and steeper position–velocity diagrams, which are interpreted as nuclear shocks due to non-circular motions. Along the filaments, and unlike other nearby AGNs, several dense molecular clumps present low HCN/HCO+(4–3) ratios (≲0.5). The filaments abruptly end in the probed transitions at r ≃ 20 pc from the AGN, but previous near-IR H2(J = 1–0)S(1) maps show that they continue in an even warmer gas phase (T ∼ 1000 K), winding up in the form of nuclear spirals, and forming an inner ring structure with another set of symmetric filaments along the N–S direction and within r ≃ 10 pc. The molecular gas is governed primarily by non-circular motions, being the successive shock fronts at different scales where loss of angular momentum occurs, a mechanism that may feed efficiently powerful radio galaxies down to parsec scales.
Free Keywords:galaxies: elliptical and lenticular; cD; galaxies: individual: NGC 5128; galaxies: structure; ISM: molecules
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-637X
URL:http://adsabs.harvard.edu/abs/2017ApJ...843..136E
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