The Discovery of H2O Maser Emission in Seven AGN and at High Velocities in the Circinus Galaxy

Abstract

We report the discovery of H2O maser emission at 1.35 cm wavelength in seven active galactic nuclei (at distances up to < 80 Mpc) during a survey conducted at the 70-m diameter antenna of the NASA Deep Space Network near Canberra, Australia. The detection rate was ∼ 4%. Two of the maser sources are particularly interesting because they display satellite high-velocity emission lines, which are a signature of emission from the accretion disks of supermassive black holes when seen edge on. Three of the masers are coincident, to within uncertainties of 0.′′2, with continuum emission sources we observed at about λ1.3 cm. We also report the discovery of new spectral features in the Circinus galaxy H2O maser that broaden the known velocity range of emission therein by a factor of ∼ 1.7. If the new spectral features originate in the Circinus accretion disk, then molecular material must survive at radii ∼ 3 times smaller than had been believed previously (∼ 0.03 pc or ∼ 2 × 105 Schwarzschild radii).