Volume 426, Number 2, November I 2004
|Page(s)||481 - 493|
|Published online||11 October 2004|
The twin-jet system in NGC 1052: VLBI-scrutiny of the obscuring torus
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: email@example.com
Accepted: 8 July 2004
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.
Key words: galaxies: individual: NGC 1052 / galaxies: individual: PKS B0238-084 / galaxies: active / galaxies: jets
© ESO, 2004
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.