Exploring the Nucleus of the Gigamaser Galaxy TXS 2226-184

Abstract

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) 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) 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.

arXiv comment17 pages including 5 figures, LaTeX. Accepted to ApJ on May 24, 2004

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Cited by in corpus (5)

• Overview on spectral line source finding and visualisation
• The interstellar and circumnuclear medium of active nuclei traced by HI 21-cm absorption
• VLBA Observations of HI in the Archetype Compact Symmetric Object B2352+495
• VLBI observations of the H2O gigamaser in TXS2226-184
• 21cm Absorption by Compact Hydrogen Disks Around Black Holes in Radio-Loud Nuclei of Galaxies