The AGN Ionization Cones of NGC 5728. II. Kinematics

Abstract

Abstract We explore the gas morphology and excitation mechanisms of the ionization cones of the type II Seyfert galaxy NGC 5728. Kinematics derived from near-infrared and optical data from the SINFONI and MUSE Integral Field Units on the VLT reveal active galactic nucleus (AGN)-driven outflows powered by a supermassive black hole (SMBH) of mass 3.4 × 107 M ⊙, bolometric luminosity of 1.46 × 1044 erg s−1, Eddington ratio of 3.3 × 10−2, and an accretion rate of 2.7 × 10−2 M ⊙ yr−1. The symmetric bicone outflows show rapid acceleration to ±250 km s−1 at ∼250 pc, decelerating to ∼130 km s−1 at 500 pc from the AGN, with an estimated mass outflow rate of 38 M ⊙ yr−1; the mass ratio of outflows to accretion is 1415. The kinetic power is ∼1.5 × 1042 erg s−1, 1% of the bolometric luminosity. Over the AGN active lifetime of ∼107 yr, 1.6 × 108 M ⊙ of gas can become gravitationally unbound from the galaxy, a large proportion of the gas mass available for star formation in the nuclear region. The bicone internal opening angle (50.°2) and the inclination to the line of sight (47.°6) were determined from [Fe ii] line profiles; the outflow axis is nearly parallel to the plane of the galaxy. This geometry supports the unified model of AGNs, as these angles preclude seeing the accretion disk, which is obscured by the dusty torus.