Massive star clusters, feedback, and superwinds

Young massive star clusters return matter and energy to the ISM via cluster winds that ultimately combine to power superwinds in high-density starbursts. We present high-resolution near-IR spectroscopy of such clusters that dominate the current star formation in the nearby merger, the Antennae. By fitting outflow models to their broad hydrogen lines, we measure the mass-loss rates and mechanical luminosities of these cluster outflows. They are strongly mass-loaded with high thermalization efficiencies, two properties that also characterize superwinds. While the Antennae do emit large-scale diffuse X-rays, their present star cluster density may be too low to generate an M82-like superwind, but it is perfect for providing a resolved look at feedback mechanisms in a young merger.