An outflow in the Seyfert ESO 362-G18 revealed by Gemini-GMOS/IFU observations^★

¹ Departamento de Astronomía, Universidad de Concepción, Casilla 160, Concepción, Chile
e-mail: phumire@udec.cl
² Departamento de Física y Astronomía, Universidad de La Serena, La Serena, Chile
³ Gemini Observatory, Southern Operations centre, La Serena, Chile
⁴ Dirección de Formacion General, Facultad de Educación y Cs. Sociales, Universidad Andres Bello, Sede Concepción, autopista Concepción-Talcahuano 7100, Talcahuano, Chile
⁵ SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
⁶ Department of Astrophysics/IMAPP, Radboud University, Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
⁷ Universidade Federal de Santa Maria, Departamento de Física, Centro de Ciencias Naturais e Exatas, 97105-900 Santa Maria, RS, Brazil
⁸ Naval Research Laboratory, Washington, DC 20375, USA
⁹ Institute for Astrophysics and Computational Sciences, Department of Physics, The Catholic University of America, Washington, DC 20064, USA
¹⁰ Instituto de Física, CP 15015, Universidade Federal do Rio Grande do Sul, 91501-970, Porto Alegre, RS, Brazil
¹¹ Astrophysics Science Division, Goddard Space Flight centre, Code 665, Greenbelt, MD 20771, USA
¹² Department of Physics, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623, USA
¹³ Department of Physics and Astronomy, Georgia State University, Astronomy Offices, 25 Park Place Suite 605, Atlanta, GA 30303, USA
¹⁴ Harvard-Smithsonian centre for Astrophysics 60 Garden St., ms.6, Cambridge MA 02138 USA

Received: 28 July 2017
Accepted: 16 February 2018

Abstract

We present two-dimensional stellar and gaseous kinematics of the inner 0.7 × 1.2 kpc² of the Seyfert 1.5 galaxy ESO 362-G18, derived from optical (4092–7338 Å) spectra obtained with the GMOS integral field spectrograph on the Gemini South telescope at a spatial resolution of ≈170 pc and spectral resolution of 36 km s⁻¹. ESO 362-G18 is a strongly perturbed galaxy of morphological type Sa or S0/a, with a minor merger approaching along the NE direction. Previous studies have shown that the [O III] emission shows a fan-shaped extension of ≈10′′ to the SE. We detect the [O III] doublet, [N II] and Hα emission lines throughout our field of view.

The stellar kinematics is dominated by circular motions in the galaxy plane, with a kinematic position angle of ≈137° and is centred approximately on the continuum peak. The gas kinematics is also dominated by rotation, with kinematic position angles ranging from 122° to 139°, projected velocity amplitudes of the order of 100 km s⁻¹, and a mean velocity dispersion of 100 km s⁻¹. A double-Gaussian fit to the [O III]λ5007 and Hα lines, which have the highest signal to noise ratios of the emission lines, reveal two kinematic components: (1) a component at lower radial velocities which we interpret as gas rotating in the galactic disk; and (2) a component with line of sight velocities 100–250 km s⁻¹ higher than the systemic velocity, interpreted as originating in the outflowing gas within the AGN ionization cone. We estimate a mass outflow rate of 7.4 × 10⁻² M_⊙ yr⁻¹ in the SE ionization cone (this rate doubles if we assume a biconical configuration), and a mass accretion rate on the supermassive black hole (SMBH) of 2.2 × 10⁻² M_⊙ yr⁻¹. The total ionized gas mass within ~84 pc of the nucleus is 3.3 × 10⁵ M_⊙; infall velocities of ~34 km s⁻¹ in this gas would be required to feed both the outflow and SMBH accretion.