A Dark Census: Statistically Detecting the Satellite Populations of Distant Galaxies

Understand

In the standard structure formation scenario based on the cold dark matter paradigm, galactic halos are predicted to contain a large population of dark matter subhalos.

• While the most massive members of the subhalo population can appear as luminous satellites and be detected in optical surveys, establishing the existence of the low mass and mostly dark subhalos has proven to be a daunting task.
• Galaxy-scale strong gravitational lenses have been successfully used to study mass substructures lying close to lensed images of bright background sources.
• However, in typical galaxy-scale lenses, the strong lensing region only covers a small projected area of the lens's dark matter halo, implying that the vast majority of subhalos cannot be directly detected in lensing observations.