Interferometric CO(3-2) Observations toward the Central Region of NGC
  1068
  We present CO(3-2) interferometric observations of the central region of the
Seyfert 2 galaxy NGC 1068 using the Submillimeter Array, together with CO(1-0)
data taken with the Owens Valley Radio Observatory Millimeter Array. Both the
CO(3-2) and CO(1-0) emission lines are mainly distributed within ~5 arcsec of
the nucleus and along the spiral arms, but the intensity distributions show
differences; the CO(3-2) map peaks in the nucleus, while the CO(1-0) emission
is mainly located along the spiral arms. The CO(3-2)/CO(1-0) ratio is about 3.1
in the nucleus, which is four times as large as the average line ratio in the
spiral arms, suggesting that the molecular gas there must be affected by the
radiation arising from the AGN. On the other hand, the line ratios in the
spiral arms vary over a wide range from 0.24 to 2.34 with a average value
around 0.75, which is similar to the line ratios of star-formation regions,
indicating that the molecular gas is affected by star formation. Besides, we
see a tight correlation between CO(3-2)/(1-0) ratios in the spiral arms and
star formation rate surface densities derived from Spitzer 8 {\mu}m dust flux
densities. We also compare the CO(3-2)/(1-0) ratio and the star formation rate
at different positions within the spiral arms; both are found to decrease as
the radius from the nucleus increases.
