2004/07/14 by M. Kadler, E. Ros, A. P. Lobanov +3 · 4 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1051/0004-6361:20041051
published as Astron.Astrophys. 426 (2004) 481-493 · 14 pages, 11 figures, needs aa.cls, accepted for publication in Astronomy & Astrophysics, note that the resolution of figure 2 has been decreased in comparison to the journal version
arxiv created 2004/07/14 · openalex publication_date 2004/10/11 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
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 ~ pc to 0.3 pc east of 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 ~ 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.