Outflows in the inner kiloparsec of NGC 1566 as revealed by molecular (ALMA) and ionized gas (Gemini-GMOS/IFU) kinematics^⋆

¹ Departamento de Astronomía, Universidad de Concepción, Casilla 160-C, Concepción, Chile
e-mail: royslater@astro-udec.cl, nagar@astro-udec.cl
² Dirección de Formación General, Facultad de Educación y Cs. Sociales, Universidad Andres Bello, Sede Concepción, autopista Concepción-Talcahuano 7100, Talcahuano, Chile
³ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstr. 1, 85741 Garching, Germany
⁴ CAPES Foundation, Ministry of Education of Brazil, 70040-020 Brasília, Brazil
⁵ Instituto de Física, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, RS, Brazil
⁶ SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
⁷ Department of Astrophysics/IMAPP, Radboud University, Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
⁸ Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK
⁹ Departamento de Física/CCNE, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil
¹⁰ Department of Astronomy, The Ohio State University, 140 W 18th Avenue, Columbus, OH 43210, USA
¹¹ Center for Cosmology and AstroParticle Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210, USA
¹² School of Physics and Astronomy, Rochester Institute of Technology, 85 Lomb Memorial Dr., Rochester, NY 14623, USA
¹³ Instituto de Física y Astronomía, Universidad de Valparaíso, Avda. Gran Bretaña 1111, Valparaíso, Chile

Received: 15 February 2017
Accepted: 27 March 2018

Abstract

Context. Tracing nuclear inflows and outflows in active galactic nuclei (AGNs), determining the mass of gas involved in them, and their impact on the host galaxy and nuclear black hole requires 3D imaging studies of both the ionized and molecular gas.

Aims. We 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.

Methods. 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.

Results. 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 favor 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 M_⊙ yr⁻¹, with this gas accumulating in the nuclear 2″ 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 M_⊙ yr⁻¹, is significantly higher than the SMBH accretion rate (ṁ = 4.8 × 10⁻⁵ M_⊙ yr⁻¹).