IC 5063 - A merger remnant with a hidden luminous active nucleus

Sensitive high spatial resolution optical and infrared imaging and optical spectroscopy are presented for the active galaxy IC 5063. Physical and kinematic conditions are derived for the emission regions, and deep images of the dust and optical line emission are presented. These support the proposition that the gas and dust arise from a recent merger event. Strong evidence is found for the presence of a hidden, luminous ionization source in the nucleus of IC 5063. This comprises the detection of a broad faint H-alpha emission line with FWZI roughly 6000 km/s, the detection of high-excitation forbidden Fe VII emission lines and the presence of an extended emission-line region with a well-defined region of high excitation. One of the best examples of a highly anisotropic ionizing radiation field is found, with the high-excitation line emission displaying a distinctive X or conical morphology. This cone has a 50 deg opening angle in projection, extends over 22 kpc and has a large-scale X-type morphology, very probably due to dust obscuration of the ionization beam. This is in turn consistent with consideration of the energetic balance between the ionized gas and infrared emission. 69 refs.