How are Bright Galaxies Embedded within their Dark Matter Halos?

Abstract Recent studies suggest that the orientations of large, bright galaxies within their dark matter halos are related to the morphologies of the galaxies themselves. Elliptical galaxies tend to be oriented such that, in projection on the sky, the mass (i.e., the dark matter) is well-aligned with the luminous galaxy. On the other hand, disk galaxies tend to be oriented such that their angular momentum vectors are aligned with the angular momenta of their halos. This results in a misalignment of mass and light, and has important implications for future studies that seek to measure the shapes of the dark matter halos that surround disk galaxies.