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Neumayer et al. established the existence of a blue-shifted cloud in the coreof Centaurus A, within a few parsecs of the nucleus and close to the radio jet.We propose that the cloud has been impacted by the jet, and that it is in theforeground of the jet, accounting for its blue-shifted emission on the Southernside of the nucleus. We consider both shock excitation and photoionizationmodels for the excitation of the cloud. Shock models do not account for the[SiVI] and [CaVIII] emission line fluxes. However, X-ray observations indicatea source of ionizing photons in the core of Centaurus A; photoionization by theinferred flux incident on the cloud can account for the fluxes in these linesrelative to Brackett-gamma. The power-law slope of the ionizing continuummatches that inferred from synchrotron models of the X-rays. The logarithm ofthe ionization parameter is -1.9, typical of that in Seyfert galaxies andconsistent with the value proposed for dusty ionized plasmas. The model clouddensity depends upon the Lorentz factor of the blazar and the inclination ofour line of sight to the jet axis. For acute inclinations, the inferred densityis consistent with expected cloud densities. However, for moderate inclinationsof the jet to the line of sight, high Lorentz factors imply cloud densities inexcess of $10^5 cm^{-3}$ and very low filling factors, suggesting that modelsof the gamma ray emission should incorporate jet Lorentz factors $\lesssim 5$.

The Kinematics and Ionization of Nuclear Gas Clouds in Centaurus A