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Paper: The Two-Sided VLBI Source in the Seyfert Galaxy MRK 231
Volume: 144, Radio Emission from Galactic and Extragalactic Compact Sources, IAU Colloquium 164
Page: 199
Authors: Ulvestad, J. S.; Wrobel, J. M.; Carilli, C. L.
Abstract: The Seyfert 1/starburst/IR galaxy Mrk 231 (UGC 08058), at z=0.0422, has been imaged with the VLBA at frequencies ranging from 1.4 GHz to 22 GHz. The radio image shows a triple source of total size 50 mas (30h^{-1} pc), with a self-absorbed central component and two detached lobes. The northern lobe, located 12h^{-1} pc from the core, is free-free absorbed at the lowest frequencies; there also seems to be free-free absorption in the southern component. The linear scale over which this absorption takes place is several times larger than that seen in NGC 1275/3C 84. The axis of the 50-mas radio source is approximately 60 degrees from the elongation of the central component on the 1-mas scale. The spectrum of this central component becomes optically thin between 5 and 8.4 GHz, and resolves into a small triple source of size ~1.0h^{-1} pc at 15 GHz. There is no hint of a jet or other structure directly connecting this central component to the outer VLBI lobes.
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