Physical and Chemical Conditions in Centaurus A

We present high-resolution maps of rotational transitions of the molecules $^{12}$C$^{16}$O, $^{13}$C$^{16}$O, $^{12}$C$^{18}$O, HCN, and HCO$^{+}$ toward the nuclear region of the nearby active galaxy, Centaurus A (Cen A). At $\sim $3.8 Mpc away, Cen A is the closest radio galaxy, so it serves as the best laboratory for determining how accretion onto a supermassive black hole affects the structure and evolution of a galaxy. The data were obtained with the Atacama Large Millimeter Array interferometer during Early Science commissioning. The CO isotopologue data reveals the morphology of Cen A. Two arm-like features were found along with a $\sim $200 pc disk-like feature associated with the supermassive black hole. The CO isotopologues preferentially trace the arms, while HCN and HCO$^{+}$, tracers of high density gas, dominate the disk feature. Large velocity gradient radiative transfer models of the CO line ratios constrain the gas in the arms to be warm (T$>$50 K) and modestly dense (n$_{H2}\sim $10$^{3}$ cm$^{-3})$. The enhanced emission from HCN and HCO$^{+}$, suggest the disk-like feature is much denser, or influenced by anomalous chemical processes from the black hole radiation field.