Red-shifted H2O emission in NGC 3079: more evidence for a pc-scale circumnuclear torus?

Abstract

Using the Effelsberg 100-m telescope, sensitive measurements of the H2O megamaser in NGC 3079 are presented. During 2000 - 2001, `high velocity' features are seen that are red-shifted up to 225 km/s with respect to the systemic velocity of the galaxy (about 1120 km/s). Symmetrically bracketing the systemic velocity, the H2O emission covers a velocity range of 450 km/s with only one potential narrow gap (20 km/s) near the systemic velocity itself. Velocity drifts of individual components are not convincingly detected. It is shown that the presence of red-shifted emission and the absence of detectable velocity drifts are not inconsistent with the existence of a rotating circumnuclear maser disk at the very center of the galaxy. Significant differences in the overall line profile compared to NGC 4258 and a complex morphology of the radio continuum leave, however, space for scepticism.

4 pages, including 3 figures. Astronomy and Astrophysics Letters, accepted

References in corpus (2)

• A 4% Geometric Distance to the Galaxy NGC4258 from Orbital Motions in a Nuclear Gas Disk
• The Nature of the Nuclear H2O Masers of NGC 1068: Reverberation and Evidence for a Rotating Disk Geometry

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