The Circumnuclear Disk Revealed by ALMA. I. Dense Clouds and Tides in the Galactic Center

Utilizing the Atacama Large Millimeter/submillimeter Array (ALMA), we present CS line maps in five rotational lines ($J_{\rm u}=7, 5, 4, 3, 2$) toward circumnuclear disk (CND) and streamers of Galactic Center. Our primary goal is to resolve compact structures within CND streamers, order understand stability conditions molecular cores vicinity supermassive black hole (SMBH) Sgr A*. data provide first homogeneous high-resolution ($1.3'' = 0.05$ pc) observations aiming at resolving density temperature structures. The clouds have sizes $0.05-0.2$ pc with a broad range velocity dispersion ($\sigma_{\rm FWHM}=5-40$ km s$^{-1}$). are mixture warm ($T_{\rm k}\ge 50-500$ K, n$_{\rm H_2}$=$10^{3-5}$ cm$^{-3}$) cold gas k}\le 50$ H_2}$=$10^{6-8}$ cm$^{-3}$). A analysis based on unmagnetized virial theorem including tidal force shows that $84^{+16}_{-37}$ % total mass tidally stable, which accounts for majority mass. Turbulence dominates internal energy thereby sets threshold densities $10-100$ times higher than limit distance $\ge 1.5$ A*, therefore, inhibits from collapsing form stars near SMBH. However, central $1.5$ pc, overrides turbulence gravitational collapse quickly grow 10^{8}$ cm$^{-3}$.