Description
Cosmology simulations show that the cosmic web environment of a dark matter halo can have a significant impact on its growth. For example, halos within thick filaments are found to be ‘stalled’ due to the tidal fields, effectively stopping the halo from gaining mass. Conversely, halos in voids are found to be continuously accreting matter. Whilst the accretion of dark matter onto a halo is not directly observable, Borzyszkowski+ 2017 were able to link the accretion to the velocity anisotropy of the halo. This means that the velocity anisotropy of galaxy groups provides a potential avenue to test the effect of cosmic web environment on halo growth.
Unfortunately, individual groups are too small to reliably measure these dynamical properties, as they only contain 10s of satellite galaxies to trace the velocity field. We aim to overcome this shortcoming by rescaling and stacking data from multiple groups so that shared underlying properties can be measured instead. This is motivated by cosmology simulations, where the mass profiles of groups are self-similar and characterised by a scale mass and scale radius, allowing for a trivial rescaling process. This poster will show a proof of concept of this stacking process, where we stacked Illustris-TNG groups to measure stacked velocity dispersions and velocity anisotropies. We also demonstrate how this stacking can be used to recover the dark matter mass profile using the Jeans equation.
