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H_2O maser and a plasma obscuring torus in the radio galaxy NGC 1052
- Source :
- Astron.Nachr.330:249-252,2009
- Publication Year :
- 2009
-
Abstract
- We present multi-frequency simultaneous VLBA observations at 15, 22 and 43 GHz towards the nucleus of the nearby radio galaxy NGC 1052. These three continuum images reveal a double-sided jet structure, whose relative intensity ratios imply that the jet axis is oriented close to the sky plane. The steeply rising spectra at 15-43 GHz at the inner edges of the jets strongly suggest that synchrotron emission is absorbed by foreground thermal plasma. We detected H_2O maser emission in the velocity range of 1550-1850 km/s, which is redshifted by 50-350 km/s with respect to the systemic velocity of NGC 1052. The redshifted maser gas appears projected against both sides of the jet, similar to the HI seen in absorption. The H_2O maser gas is located where the free-free absorption opacity is large. This probably implies that the masers in NGC 1052 are associated with a circumnuclear torus or disk as in the nucleus of NGC 4258. Such circumnuclear structure can be the sense of accreting onto the central engine.<br />Comment: 4 pages, 5 figures, accepted for publication in Astronomische Nachrichten (issue dedicated to the Proceedings of "The 4th Workshop on Compact Steep Spectrum and GHz-Peaked Spectrum Radio Sources" held at Riccione, Italy, 26-29 May 2008)
- Subjects :
- Astrophysics - Cosmology and Extragalactic Astrophysics
Subjects
Details
- Database :
- arXiv
- Journal :
- Astron.Nachr.330:249-252,2009
- Publication Type :
- Report
- Accession number :
- edsarx.0902.4068
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1002/asna.200811168