The Inner 200pc: Hot Dense Molecular Gas in the Galactic Center

Christopher L. Martin1, Antony A. Stark1, Adair P. Lane1

1 Harvard-Smithsonian Center for Astrophysics, 60 Garden St., MS-12, Cambridge, MA 02138

E-mail contact: cmartin@cfa.harvard.edu

Using CO(7-6) (807 GHz), CO(4-3) (461 GHz), CI(3P2-3P1) (809 GHz), and CI(3P1-3P0) (492 GHz) emission we are able use an LVG model to estimate the kinetic temperature and density of molecular gas in the inner 200pc region of the Galactic Center. We find that after excluding the hot dense clouds, the average kinetic temperature of the molecular gas is 35 +/- 10 K. With our velocity resolution of 0.6 km/s, we are also able to show the distribution of gas spatial density and kinetic temperature as a function of position and velocity for the entire region. The data used come from a fully-sampled one and a half square degree region of the Galactic Center taken with the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) in 2001-02. The data cover -1.3 deg < l < 2 deg, -0.3 deg < b < 0.2 deg, with 0.5' spacing resulting in over 24,000 spectra. Bright CO(7-6) emission is detected in the well-known Galactic Center clouds Sgr A and Sgr B, as well as in numerous other features. We also detect CO(4-3) and CO(7-6) absorption at vLSR = -4 km/s along the line of sight toward the Galactic Center.