The offsets between galaxies and their dark matter in Lambda-CDM

Understand

We use the "Evolution and Assembly of GaLaxies and their Environments" ( EAGLE ) suite of hydrodynamical cosmological simulations to measure offsets between the centres of stellar and dark matter components of galaxies.

• We find that the vast majority (>95%) of the simulated galaxies display an offset smaller than the gravitational softening length of the simulations (Plummer-equivalent $\epsilon = 700$ pc), both for field galaxies and satellites in clusters and groups.
• We also find no systematic trailing or leading of the dark matter along a galaxy's direction of motion.
• The offsets are consistent with being randomly drawn from a Maxwellian distribution with $\sigma \leq 196$ pc.