We present Very Long Baseline Array (VLBA) observations of the Gigamaser galaxy TXS2226-184 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 has no readily identifiable flat-spectrum active nucleus. This morphology resembles that of the nearby compact starburst galaxy Mrk 273, although no significant FIR emission has been detected to support the starburst scenario. The narrow (125 km s−1) Hi absorption in TXS2226-184 discovered with the VLA is also detected with the VLBA. This Hi absorption is distributed across the extended emission, probably co-spatial with the water masers. The broad (420 km s−1) line seen by the VLA is not detected, suggesting that it arises from more extended gas which is absorbing the emission beyond the central tens of parsecs. (Refer to PDF file for exact formulas).

Publication Date



Also archived in: arXiv:astro-ph/0405484 v1 25 May 2004 This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, Caltech, under contract with NASA. This research has also made use of NASA’s Astrophysics Data System Abstract Service.ISSN:1538-4357 Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type


Department, Program, or Center

School of Physics and Astronomy (COS)


RIT – Main Campus