Institution(s): 1. University of Hawaii
Large-scale galactic outflows, caused by high levels of star formation or by active galactic nuclei (AGN), have important effects on galaxies' evolution. Such outflows are assumed to regulate star formation, redistribute metals within a galaxy, and potentially contribute to reionization at high redshifts. However, the launching mechanism for these outflows is still debated theoretically. We use high spatial resolution narrow-band imaging to investigate the small-scale origins of these large-scale outflows. In this talk, I'll present new HST/WFC3 narrow-band imaging that reveals a previously undiscovered Halpha+[NII] bubble feature in the circumnuclear region in Arp 220, a late-stage galaxy merger. This feature measures 1.6'' in diameter, or 600 pc, is only 1'' northwest of the western nucleus, and is aligned with the large-scale outflow seen in X-rays. I will discuss several possibilities for the bubble origin, including feedback from a low-luminosity AGN and high levels of star formation.