Exploring the Nucleus of the Gigamaser Galaxy TXS 2226–184

• Published in: The Astrophysical journal 2004-09, Vol.612 (2), p.780-785
• Main Authors: Taylor, G. B, Peck, A. B, Ulvestad, J. S, O’Dea, C. P
• Format: Article
• Language: English
• Subjects: Active and peculiar galaxies (including bl lacertae objects, blazars, seyfert galaxies, markarian galaxies, active galactic nuclei); Astronomy; Earth, ocean, space; Exact sciences and technology; Quasars. Active or peculiar galaxies, objects, and systems; Stellar systems. Galactic and extragalactic objects and systems. The universe
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1086/422746

We present Very Long Baseline Array (VLBA) observations of the gigamaser galaxy TXS 2226-184 at 1.3 and 5 GHz. These observations reveal the parsec- scale radio structure of this Seyfert galaxy with exceptionally luminous water maser emission. The source is found to be extended on scales of 10-100 pc with some embedded compact sources, but it has no readily identifiable flat-spectrum active nucleus. This morphology resembles that of the nearby compact starburst galaxy Mrk 273, although no significant far-infrared emission has been detected to support the starburst scenario. The narrow (125 km s super(-1)) H I absorption in TXS 2226-184 discovered with the Very Large Array (VLA) is also detected with the VLBA. This H I absorption is distributed across the extended emission, probably cospatial with the water masers. The broad (420 km s super(-1)) line seen by the VLA is not detected, suggesting that it arises from more extended gas that is absorbing the emission beyond the central tens of parsecs.