OPTICAL IFU OBSERVATIONS OF THE BRIGHTEST CLUSTER GALAXY NGC 4696: THE CASE FOR A MINOR MERGER AND SHOCK-EXCITED FILAMENTS

We present deep optical integral-field spectroscopic observations of the nearby ( z similar to 0.01) brightest cluster galaxy NGC 4696 in the core of the Centaurus Cluster, made with the Wide Field Spectrograph on the Australian National University 2.3 m telescope at Siding Spring Observatory. We investigate the morphology, kinematics, and excitation of the emission-line filaments and discuss these in the context of a model of a minor merger. We suggest that the emission-line filaments in this object have their origin in the accretion of a gas-rich galaxy and that they are excited by v similar to 100-200 km s(-1) shocks driven into the cool filament gas by the ram pressure of the transonic passage of the merging system through the hot halo gas of NGC 4696.