We have surveyed the central molecular zone ( CMZ ) of our Galaxy in the CO J =3–2 line with the Atacama Submillimeter-wave Telescope Experiment ( ASTE ) .
Molecular gas in the Galactic center shows high J =3–2/ J =1–0 intensity ratio ( \sim 0.9 ) while gas in the spiral arms in the Galactic disk shows the lower ratio ( \sim 0.5 ) .
The high-velocity compact cloud CO 0.02–0.02 and the hyperenergetic shell CO 1.27+0.01 , as well as gas in the Sgr A region exhibit high J =3–2/ J =1–0 intensity ratio exceeding 1.5 .
We also found a number of small spots of high ratio gas .
Some of these high ratio spots have large velocity widths and some seem to associate with nonthermal threads or filaments .
These could be spots of hot molecular gas shocked by unidentified supernovae which may be abundant in the CMZ .