NGC 1052 offers the possibility to study the obscuring torus around a supermassive black hole , predicted by the standard model of active galactic nuclei , over a wide range of wavelengths from the radio to the X-ray regime .
We present a detailed VLBI study of the parsec-scale structure of the “ twin-jet ” system in NGC 1052 in both total and polarized intensity and at multiple frequencies .
We report the detection of linearly polarized emission from the base of the eastern jet at 5 GHz .
While the radio spectrum in this region might be still consistent with synchrotron self absorption , the highly inverted spectrum of the western jet base represents a clear sign of pronounced free-free absorption in a circumnuclear torus .
We observe an abrupt change of the brightness temperature gradient at a distance of \sim 0.2 pc to 0.3 pc from the central engine .
This might provide an observational signature of the edge of the central torus , where the transition from an external pressure-dominated jet regime to a more or less freely expanding jet takes place .
We determine the absorbing column density towards the western jet core to be \sim 2.2 \times 10 ^ { 22 } cm ^ { -2 } in good agreement with the values derived from various X-ray observations .
This suggests that the nuclear X-ray emission and the jet emission imaged by VLBI originate on the same scales .