A Search for H_2O Maser Emission Toward Active Galactic Nuclei: Discovery of a Nuclear Maser Source in NGC 3735

摘要

We report the results of a survey for H2O maser emission in the 6_165_23 transition at 1.35 cm wavelength in 29 active galactic nuclei (AGNs). One new maser was detected. The detection rate among objects with recessional velocities <7000 km s~-1 is consistent with rates reported elsewhere for similarly nearby objects (about one in 15). The new maser lies in the edge-on Seyfert 2 galaxy NGC 3735 (inclination 77 deg ) within 10 km s~-1 of the systemic velocity. No other emission has been identified at velocities within ±500 km s~-1 of the systemic velocity. The maser is coincident with the radio continuum peak of the nucleus at 6 and 3.6 cm wavelengths to within the estimated 1 σastrometric uncertainty of 0".1 (15 pc at a distance of 30 Mpc).