High-density Molecular Gas Properties of the Starburst Galaxy NGC 1614
  Revealed with ALMA
  We present the results of HCN/HCO+/HNC J=4-3 transition line observations of
the nearby starburst galaxy NGC 1614, obtained with ALMA Cycle 0. We find that
high density molecular gas, traced with these lines, shows a velocity structure
such that the northern (southern) side of the nucleus is redshifted
(blueshifted) with respect to the nuclear velocity of this galaxy. The
redshifted and blueshifted emission peaks are offset by ~0.6" at the northern
and southern sides of the nucleus, respectively. At these offset positions,
observations at infrared >3 micron indicate the presence of active dusty
starbursts, supporting the picture that high-density molecular gas is the site
of active starbursts. The enclosed dynamical mass within the central ~2" in
radius, derived from the dynamics of the high-density molecular gas, is ~10^9
Msun, which is similar to previous estimates. Finally, the HCN emission is
weaker than HCO+ but stronger than HNC for J=4-3 for all starburst regions of
NGC 1614, as seen for J=1-0 transition lines in starburst-dominated galaxies.
