2MASX J00423991+3017515: An offset active galactic nucleus in an
  interacting system
  We present a spectroscopic and imaging study of an abnormal active galactic
nucleus (AGN), 2MASX J00423991+3017515. This AGN is newly identified in the
hard X-rays by the Swift BAT All-Sky survey and found in an edge-on disk galaxy
interacting with a nearby companion. Here, we analyze the first optical spectra
obtained for this system (taken in 2011 and 2016), high-resolution imaging
taken with the Hubble Space Telescope and Chandra X-ray Observatory, and 1"
imaging with the Very Large Array. Two unique properties are revealed: the
peaks of the broad Balmer emission lines (associated with gas orbiting very
near the supermassive black hole) are blue shifted from the corresponding
narrow line emission and host galaxy absorption by 1540 km/s, and the AGN is
spatially displaced from the apparent center of its host galaxy by 3.8 kpc. We
explore several scenarios to explain these features, along with other
anomalies, and propose that 2MASX J00423991+3017515 may be an AGN with an
unusually strong wind residing in a uniquely configured major merger, or that
it is an AGN recoiling from either a gravitational "slingshot" in a three-body
interaction or from a kick due to the asymmetric emission of gravitational
waves following the coalescence of two progenitor supermassive black holes.
