ALMA 0.1-0.2 arcsec resolution imaging of the NGC 1068 nucleus - compact
  dense molecular gas emission at the putative AGN location
  We present the results of our ALMA Cycle 2 high angular resolution (0.1-0.2
arcsec) observations of the nuclear region of the nearby well-studied type-2
active galactic nucleus (AGN), NGC 1068, at HCN J=3-2 and HCO+ J=3-2 emission
lines. For the first time, due to a higher angular resolution than previous
studies, we clearly detected dense molecular gas emission at the putative AGN
location, identified as a ~1.1 mm (~266 GHz) continuum emission peak, by
separating this emission from brighter emission located at 0.5-2.0 arcsec on
the eastern and western sides of the AGN. The estimated intrinsic molecular
emission size and dense molecular mass, which are thought to be associated with
the putative dusty molecular torus around an AGN, were ~10 pc and ~several x
10^5 Msun, respectively. HCN-to-HCO+ J=3-2 flux ratios substantially higher
than unity were found throughout the nuclear region of NGC 1068. The continuum
emission displayed an elongated morphology along the direction of the radio jet
located at the northern side of the AGN, as well as a weak spatially resolved
component at ~2.0 arcsec on the southwestern side of the AGN. The latter
component most likely originated from star formation, with the estimated
luminosity more than one order of magnitude lower than the luminosity of the
central AGN. No vibrationally excited (v2=1f) J=3-2 emission lines were
detected for HCN and HCO+ across the field of view.
