2008ApJ...685L..39D

We report the detection of water maser emission from four nearby galaxies hosting ultradense H II (UDHII) regions, He 2-10, the Antennae galaxies (NGC 4038/4039), NGC 4214, and NGC 5253, with the Green Bank Telescope. Our detection rate is 100%, and all of these H₂ O ``kilomasers'' (L_H2_O<10 L_☉) are located toward regions of known star formation as traced by UDHII regions and bright 24 µm emission. Some of the newly discovered H₂ O masers have luminosities 1-2 orders of magnitude less than previous extragalactic studies and the same order of magnitude as those typical of Galactic massive star-forming regions. The unusual success of this minisurvey suggests that H₂ O maser emission may be very common in starburst galaxies, and the paucity of detections to date is due to a lack of sufficient sensitivity. While the galaxy sample was selected by the presence of UDHII regions, and the UDHII regions lie within the telescope beam, in the absence of H₂ O spectral line maps the connection between H₂ O masers and UDHII regions has not yet been demonstrated.