SMA observations of Haro 2: molecular gas around a hot superbubble

Abstract

ABSTRACT Haro 2, a nearby dwarf starburst dwarf galaxy with strong Ly α emission, hosts a starburst that has created outflows and filaments. The clear evidence for galactic outflow makes it an ideal candidate for studying the role of molecular gas in feedback processes in a dwarf galaxy. We observed CO(2–1) in Haro 2 at the Submillimeter Array in the compact and extended configurations, and have mapped the molecular emission with velocity resolution 4.1 km s−1 and spatial resolution 2.0 × 1.6 arcsec2. With this significant increase of resolution over previous measurements, we see that the molecular gas comprises two components: bright clumps associated with the embedded star clusters of the starburst, and fainter extended emission east of the starburst region. The extended emission coincides with an X-ray bubble and has the kinematic signatures of an outflowing cone or of an expanding shell or bubble; the velocity range is ∼35 km s−1. We suggest that the starburst winds that created the X-ray bubble have entrained the molecular gas, and that the apparent velocity gradient at an angle to the photometric axis is an artefact caused by the outflow. The molecular and X-ray activity is on the east of the galaxy and the ionized outflow and optical filaments are west; their relationship is not clear.