Outflows in the inner kilosparsec of NGC 1566 as revealed by molecular (ALMA) and ionized gas (Gemini-GMOS/IFS) kinematics

R. Slater, C. Finlez, N. M Nagar, A. Schnorr-Muller, T. Storchi-Bergmann, V. Ramakrishnan, Carole Mundell, R. A. Riffel, B. Peterson, A. Robinson, G. Orellana

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We aim to map the distribution and kinematics of molecular and ionized gas in a sample of active galaxies, to quantify the nuclear inflows and outflows. Here, we analyze the nuclear kinematics of NGC 1566 via ALMA observations of the CO J:2-1 emission at 24 pc spatial and ∼2.6 km s−1 spectral resolution, and Gemini-GMOS/IFU observations of ionized gas emission lines and stellar absorption lines at similar spatial resolution, and 123 km s−1 of intrinsic spectral resolution. The morphology and kinematics of stellar, molecular (CO) and ionized ([N II]) emission lines are compared to the expectations from rotation, outflows, and streaming inflows. While both ionized and molecular gas show rotation signatures, there are significant non-circular motions in the innermost 200 pc and along spiral arms in the central kpc (CO). The nucleus shows a double-peaked CO profile (Full Width at Zero Intensity of 200 km s−1), and prominent (∼80 km s−1) blue and redshifted lobes are found along the minor axis in the inner arcseconds. Perturbations by the large-scale bar can qualitatively explain all features in the observed velocity field. We thus favour the presence of a molecular outflow in the disk with true velocities of ∼180 km s−1 in the nucleus and decelerating to 0 by ∼72 pc. The implied molecular outflow rate is 5.6 [Moyr−1], with this gas accumulating in the nuclear 2 arcsec arms. The ionized gas kinematics support an interpretation of a similar, but more spherical, outflow in the inner 100 pc, with no signs of deceleration. There is some evidence of streaming inflows of ∼50 km s−1 along specific spiral arms, and the estimated molecular mass inflow rate, ∼0.1 [Moyr−1], is significantly larger than the SMBH accretion rate (m˙=4.8×10−5 [Moyr−1]).
Original languageEnglish
Number of pages23
JournalAstronomy & Astrophysics
Publication statusAcceptance date - 29 Mar 2018


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