The radio-loud narrow-line Seyfert 1 galaxy 1H 0323+342 in a galaxy
  merger
  The supermassive black holes (SMBHs) of narrow-line Seyfert 1 galaxies
(NLS1s) are at the lowest end of mass function of active galactic nuclei (AGNs)
and preferentially reside in late-type host galaxies with pseudobulges, which
are thought to be formed by internal secular evolution. On the other hand, the
population of radio-loud NLS1s presents a challenge for the relativistic jet
paradigm that powerful radio jets are exclusively associated with very high
mass SMBHs in elliptical hosts, which are built-up through galaxy mergers. We
investigated distorted radio structures associated with the nearest gamma-ray
emitting, radio-loud NLS1 1H 0323+342. This provides supporting evidence for
the merger hypothesis based on the past optical/near-infrared observations of
its host galaxy. The anomalous radio morphology consists of two different
structures, the inner curved structure of currently active jet and the outer
linear structure of low-brightness relics. Such a coexistence might be
indicative of the stage of an established black hole binary with precession
before the black holes coalesce in the galaxy merger process. 1H 0323+342 and
other radio-loud NLS1s under galaxy interactions may be extreme objects on the
evolutionary path from radio-quiet NLS1s to normal Seyfert galaxies with larger
SMBHs in classical bulges through mergers and merger-induced jet phases.
