Probing Halos with PNe: Mass and Angular Momentum in Early-Type Galaxies
  We present an observational survey program using planetary nebulae, globular clusters, and X-ray emission to probe the halos of early-type galaxies. We review evidence for scanty dark matter halos around ordinary elliptical galaxies, and discuss the possible implications. We also present measurements of rotation in the halos. 
Aaron J. Romanowsky