AAS 205th Meeting, 9-13 January 2005
Session 27 Active Galactic Nuclei
Poster, Monday, January 10, 2005, 9:20am-6:30pm, Exhibit Hall

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[27.10] A GBT Atlas of H2O Masers in Galactic Nuclei

J. Braatz (NRAO), C. Henkel (MPIfR), A.S. Wilson (UMD), L.J. Greenhill, J.M. Moran (CfA)

Water vapor masers have been detected toward the nuclei of some 63 galaxies, nearly all AGNs. We are using the Green Bank Telescope (GBT) to obtain sensitive spectra of most of the masers available in the northern sky. The spectra cover 380 MHz (roughly 5100 km/s) with a channel spacing of 24 kHz (0.3 km/s) at sensitivities ranging from 2 to 5 mJy per 24 kHz channel. This atlas serves to advance studies of maser phenomenology, to reveal new maser features, to identify galaxies with weak, broad emission components, and to provide a base for long-term variability studies. Several maser systems include Doppler components which are symmetrically red- and blue-shifted from the systemic recession velocity, a signature of a maser in an accretion disk. We have been monitoring the disk masers in the galaxies NGC 1386, IC 2560, Mrk 1419, and NGC 6323 in order to track velocity drifts among individual features, and thereby measure the centripetal acceleration of gas in the disk. We use these measurements to obtain an estimate of the central black hole mass in each source.

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© 2004. The American Astronomical Society.