IMF Variation in M82 Super Star Clusters

Abstract

The nuclear starburst in M82 is host to over 20 infrared-bright, dense, young super star clusters (SSCs). We use high-resolution near-infrared Keck/NIRSPEC echelle spectroscopy to measure the stellar velocity dispersions. The SSCs are resolved in Hubble Space Telescope images, from which we measure half-light radii and integrated luminosities. We calculate virial masses for the SSCs, and compare the observed light-to-mass ratios to population synthesis models to constrain the initial mass function. There are apparent variations of the IMF within this single starburst galaxy. We present evidence for mass segregation despite the young ages, and discuss implications for the interpretation of the IMF.