Extended Tidal Structure in Two Lyα-emitting Starburst Galaxies
Cannon, John M.; Skillman, Evan D.; Östlin, Göran; Leitherer, Claus; Kunth, Daniel; Mas-Hesse, Miguel; Petrosian, Artashes
United States, France, Spain, Sweden, Chile
Abstract
We present new Very Large Array (VLA) C-configuration H I imaging of the Lyα-emitting starburst galaxies Tol 1924-416 and IRAS 08339+6517. The effective resolution probes neutral gas structures larger than 4.7 kpc in Tol 1924-416 and larger than 8.1 kpc in IRAS 08339+6517. Both systems are revealed to be tidally interacting: Tol 1924-416 with ESO 338-IG04B (6.6m=72 kpc minimum separation), and IRAS 08339+6517 with 2MASX J08380769+6508579 (2.4m=56 kpc minimum separation). The H I emission is extended in these systems, with tidal tails and debris between the target galaxies and their companions. Since Lyα emission has been detected from both of these primary systems, these observations suggest that the geometry of the interstellar medium is one of the factors affecting the escape fraction of Lyα emission from starburst environments. Furthermore, these observations argue for the importance of interactions in triggering massive star formation events.