The outer haloes of massive elliptical galaxies

Massive elliptical galaxies are often found at the centres of groups and clusters of galaxies. They are thought to reside in hot gas that emits in the X-ray part of the spectrum. The gas has been captured by the massive dark matter haloes in which they reside. Although we can’t see the bulk of the stellar populations out here, we can detect planetary nebulae (PNe), which are expanding, glowing shells of ionized gas ejected from red giant stars late in their lives.

deriving mass profiles to the outer regions using x-rays

modelling the dynamics in the outer haloes