  We report results from HST/NICMOS 2 micron imaging polarimetry of the central
region of Centaurus A. In the vicinity of the nucleus we observe a complex
polarization structure which we explain by a combination of scattering of
nuclear light and dichroic polarization associated with the dust lane. The
scattered nuclear radiation is found in an angular region which extends over ~
70 degrees and thus it does not originate from a highly collimated beam, but is
associated with more omni-directional nuclear illumination. These observations
also show the presence of an unresolved, highly polarized (P = 11.1 %) nuclear
source whose polarization angle PA = 148.2 degrees is perpendicular to the jet
axis. We set an upper limit of 0.04'' (~0.8 pc) to its extent. The observed
nuclear polarization is naturally accounted for if we are observing scattered
light from an otherwise obscured nucleus provided that both the scattering
region and the occulting torus are extremely compact, with an outer radius of
less than ~ 1 pc. Alternatively, we might be directly seeing the infrared
counterpart of the radio core, similar to those found in other low luminosity
radio-galaxies observed with HST. We discuss these results in the framework of
the FRI / BL Lac unifying model.
