Stellar Velocity Dispersion: Linking Quiescent Galaxies to their Dark Matter Halos

Understand

We analyze the Illustris-1 hydrodynamical cosmological simulation to explore the stellar velocity dispersion of quiescent galaxies as an observational probe of dark matter halo velocity dispersion and mass.

• Stellar velocity dispersion is proportional to dark matter halo velocity dispersion for both central and satellite galaxies.
• The dark matter halos of central galaxies are in virial equilibrium and thus the stellar velocity dispersion is also proportional to dark matter halo mass.
• This proportionality holds even when a line-of-sight aperture dispersion is calculated in analogy to observations.