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 non-barred nearby Seyfert 2 galaxy NGC 2110. We combine Integral Field optical spectroscopy, with long-slit and WFPC2 imaging available in the HST archive to investigate the fueling mechanism in this galaxy. Previous work (Wilson & Baldwin 1985) 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 based on the stellar kinematics, 2D ionized gas velocity field and dispersion velocity, and high spatial resolution morphology at V, I and Halpha reveals that: 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 2D distribution of the emission line widths suggests the presence of a minor axis galactic outflow. 4) The nucleus is blue-shifted with respect to the stellar systemic velocity, suggesting the NLR gas is out-flowing due to the interaction with the radio jet. 5) The ionized gas is red-shifted ~100 km/s over the corresponding rotational motion south of the nucleus, and 240 km/s with respect to the nuclear stellar systemic velocity. This velocity is coincident with the HI red-shifted absorption velocity detected by Gallimore et al (1999). We discuss the possibility that the kinematics of the south ionized gas could be perturbed by the collision with a small satellite that impacted on NGC 2110 close to the center with a highly inclined orbit. Additional support for this interpretation are the radial dust lanes and tidal debris detected in the V un-sharp masked image. We suggest that a minor-merger may have driven the nuclear activity in NGC 2110.