Is a Minor Merger Driving the Nuclear Activity in the Seyfert 2 Galaxy NGC 2110?

Abstract

We report on a detailed morphological and kinematic study of the isolated nonbarred nearby Seyfert 2 galaxy NGC 2110. We combine integral field optical spectroscopy with long-slit and WFPC2 imaging available in the Hubble Space Telescope archive to investigate the fueling mechanism in this galaxy. Previous work (Wilson & Baldwin) concluded that the kinematic center of the galaxy is displaced ~220 pc from the apparent mass center of the galaxy, and the ionized gas follows a remarkably normal rotation curve. Our analysis, which is based on the stellar kinematics, two-dimensional ionized gas velocity field and dispersion velocity, and high spatial resolution morphology at V, I, and Hα, reveals the following: (1) The kinematic center of NGC 2110 is at the nucleus of the galaxy. (2) The ionized gas is not in pure rotational motion. (3) The morphology of the two-dimensional distribution of the emission-line widths suggests the presence of a minor axis galactic outflow. (4) The nucleus is blueshifted with respect to the stellar systemic velocity, suggesting the narrow-line region gas is outflowing owing to the interaction with the radio jet. (5) The ionized gas is redshifted ~100 km s -1 over the corresponding rotational motion south of the nucleus and 240 km s -1 with respect to the nuclear stellar systemic velocity. This velocity is coincident with the H I redshifted absorption velocity detected by Gallimore et al. We discuss the possibility that the kinematics of the south ionized gas could be perturbed by a collision with a small satellite that impacted on NGC 2110 close to the center with a highly inclined orbit. Additional supports for this interpretation are the radial dust lanes and tidal debris detected in the V unsharp-masked image. We suggest that a minor merger may have driven the nuclear activity in NGC 2110.