A Multi-Transition Study of Molecules toward NGC 1068 based on
  High-Resolution Imaging Observations with ALMA
  We present 0.8-mm band molecular images and spectra obtained with the Atacama
Large Millimeter/submillimeter Array (ALMA) toward one of the nearest galaxies
with an active galactic nucleus (AGN), NGC 1068. Distributions of CO isotopic
species ($^{13}$CO and C$^{18}$O) $\it{J}$ = 3--2, CN $\it{N}$ = 3--2 and CS
$\it{J}$ = 7--6 are observed toward the circumnuclear disk (CND) and a part of
the starburst ring with an angular resolution of $\sim$1.$^{\prime\prime}$3
$\times$ 1.$^{\prime\prime}$2. The physical properties of these molecules and
shock-related molecules such as HNCO, CH$_{3}$CN, SO, and CH$_{3}$OH detected
in the 3-mm band were estimated using rotation diagrams under the assumption of
local thermodynamic equilibrium. The rotational temperatures of the CO isotopic
species and the shock-related molecules in the CND are, respectively, 14--22 K
and upper limits of 20--40 K. Although the column densities of the CO isotopic
species in the CND are only from one-fifth to one-third of that in the
starburst ring, those of the shock-related molecules are enhanced by a factor
of 3--10 in the CND. We also discuss the chemistry of each species, and compare
the fractional abundances in the CND and starburst ring with those of Galactic
sources such as cold cores, hot cores, and shocked molecular clouds in order to
study the overall characteristics. We find that the abundances of shock-related
molecules are more similar to abundances in hot cores and/or shocked clouds
than to cold cores. The CND hosts relatively complex molecules, which are often
associated with shocked molecular clouds or hot cores. Because a high X-ray
flux can dissociate these molecules, they must also reside in regions shielded
from X-rays.
