2010ApJ...716L..51B

We present Very Large Array (VLA) observations with 80 mas resolution (∼9 pc) of the recently discovered Galactic-analog (GA)-H₂ O masers in the Antennae interacting galaxies (NGC 4038/NGC 4039; Arp244). Three regions of water maser emission are detected: two in the "interaction region" (IAR) and the third ∼5{farcs}6 (≳600 pc) west of the NGC 4039 nucleus. The isotropic H₂ O maser luminosities range from 1.3 to 7.7 L_☉. All three maser regions are mostly obscured in the optical/near-infrared continuum, and are coincident with massive CO-identified molecular clouds. The H₂O maser velocities are in excellent agreement with those of the molecular gas. We also present archival VLA 3.6 cm data with ∼0{farcs}28 (∼30 pc) and ∼0{farcs}8 (∼90 pc) resolution toward the maser locations. All three maser regions are coincident with compact 3.6 cm radio continuum emission, and two are dominated by thermal ionized gas, suggesting the presence of natal super star clusters containing the equivalent of a few thousand O stars. We also present detailed comparisons between the radio data and existing Hubble Space Telescope Advanced Camera for Surveys (optical) and NICMOS (near-IR) data and find that both maser regions in the IAR are also associated with Paα emission and neither source is detected shortward of 2 µm. These results highlight the potential of using GA-H₂ O masers to pinpoint sites of young super star cluster formation with exquisite angular resolution.