The CARMA 3 mm Survey of the Inner 0.7 x 0.4 degrees of the Central Molecular Zone

Abstract

The Central Molecular Zone (CMZ) of the Galactic Center has to date only been fully mapped at mm wavelengths with singledish telescopes, with resolution about 30 arcseconds (1.2 pc). Using the Combined Array for Research in Millimeter Astronomy (CARMA), we mapped the innermost 0.25 square degrees of the CMZ over the region between -0.2 < l < 0.5 degrees and -0.2 < b < 0.2 degrees (90 x 50 pc) with spatial and spectral resolution of 10 arcseconds (0.4 pc) and 2.5 km/s, respectively. We provide a catalog of 3 mm continuum sources as well as spectral line images of SiO(J=2-1), HCO+(J=1-0), HCN(J=1-0), N2H+(J=1-0), and CS(J=2-1) , with velocity coverage VLSR= -200 to 200 km/s To recover the large scale structure resolved out by the interferometer, the continuum-subtracted spectral line images were combined with data from the Mopra 22-m telescope survey, thus providing maps containing all spatial frequencies down to the resolution limit. We find that integrated intensity ratio of I(HCN)/I(HCO+) is anti-correlated with the intensity of the 6.4 keV Fe Kalpha, which is excited either by high energy photons or low energy cosmic rays, and the gas velocity dispersion as traced by HCO+ is correlated with Fe Kalpha intensity. The intensity ratio and velocity dispersion patterns are consistent with variation expected from the interaction of low energy cosmic rays with molecular gas.