A Search for H 2 O Maser Emission in Southern Active Galactic Nuclei and Star‐forming Galaxies: Discovery of a Maser in the Edge‐on Galaxy IRAS F01063?8034

Abstract

We report the cumulative results of five surveys for H2O maser emission at 1.35 cm wavelength in 131 active galactic nuclei (AGNs) and star-forming galaxies, conducted at the Parkes Observatory between 1993 and 1998. We detected one new maser, in the edge-on galaxy IRAS F01063-8034, which exhibits a single, ∼ 0.1 Jy spectral feature at 4282 ± 6 km s−1 (heliocentric) with an unusually large 54 ±16 km s−1 half-power full width. The centroid velocity of the emission increased to 4319.6 ±0.6 km s−1 (38 ±2 km s−1 width) over the 13 days between discovery and confirmation of the detection. A similarly broad linewidth and large change in velocity has been noted for the maser in NGC 1052, wherein jet activity excites the emission. Neither optical spectroscopy, radio-infrared correlations, nor infrared colors provide compelling evidence of unusual activity in the nucleus of IRAS F01063-8034. Since the galaxy appears to be outwardly normal at optical and infrared wavelengths, detection of an H2O maser therein is unique. The maser emission is evidence that the galaxy harbors an AGN that is probably obscured by the edge-on galactic disk. The detection highlights the possibility that undetected AGNs could be hidden in other relatively nearby galaxies. No other maser emission features have been identified at velocities between 3084 km s−1 and 6181 km s−1.