Detection of a Parsec-Scale Jet in a Radio-Quiet Narrow-Line Seyfert 1
  Galaxy with Highly Accreting Supermassive Black Hole
  The jet in active galactic nuclei (AGN) is a key ingredient in understanding
the co-evolution of galaxies and their central supermassive black holes
(SMBHs). Unfortunately, the mechanism of jet launching and collimation is still
elusive. The observational evidence of decreasing radio loudness with
increasing Eddington ratio implies that the jet should be coupled with the
accretion process. To further explore the relationship between the jet and
accretion, it is necessary to extend our knowledge of the jet to an extreme end
of the Eddington ratio distribution of AGN. Using Very Long Baseline Array
(VLBA), we report the detection of the parsec-scale radio structure in Mrk 335,
a radio-quiet narrow-line Seyfert 1 galaxy with an Eddington ratio close
to/above unity. The VLBA image at 1.5 GHz reveals an elongated structure
extending $\sim20$ parsec in north-south direction with a peak flux density of
$1.98\pm0.05$ mJy/beam and radio brightness temperatures as high as
$6\times10^{7}$ K. This feature provides a strong evidence of a parsec-scale
(bipolar) jet launched from a highly accreting SMBH. We discuss the result by
comparing Mrk 335 with other highly accreting systems, e.g. Galactic black
holes and tidal disruption events, and recall the discovery of collimated
corona in the vicinity of SMBH in Mrk 335 by previous X-ray observations, whose
relation to the parsec-scale radio jet should be explored by future
simultaneous X-ray spectroscopy and high resolution radio observations.
