Abstract
We present the distribution and kinematics of the molecular gas in the circumnuclear disk (CND; 400 pc x 200 pc) of Centaurus A with resolutions of similar to 5 pc (0."3) and shed light onto the mechanism feeding the active galactic nucleus (AGN) using CO(3-2), HCO+(4-3), HCN(4-3), and CO(6-5) observations obtained with ALMA. Multiple filaments or streamers of tens to a hundred parsec scale exist within the CND, which form a ring-like structure with an unprojected diameter of 9" x 6" (162 pc x 108 pc) and a position angle P.A. similar or equal to 155 degrees. Inside the nuclear ring, there are two leading and straight filamentary structures with lengths of about 30-60 pc at P.A. similar or equal to 120 degrees on opposite sides of the AGN, with a rotational symmetry of 180 degrees and steeper position-velocity diagrams, which are interpreted as nuclear shocks due to non-circular motions. Along the filaments, and unlike other nearby AGNs, several dense molecular clumps present low HCN/HCO+(4-3) ratios ((sic)0.5). The filaments abruptly end in the probed transitions at r similar or equal to 20 pc from the AGN, but previous near-IR H-2(J = 1-0)S(1) maps show that they continue in an even warmer gas phase (T similar to 1000 K), winding up in the form of nuclear spirals, and forming an inner ring structure with another set of symmetric filaments along the N-S direction and within r similar or equal to 10 pc. The molecular gas is governed primarily by non-circular motions, being the successive shock fronts at different scales where loss of angular momentum occurs, a mechanism that may feed efficiently powerful radio galaxies down to parsec scales.