A correlation between accreted stellar kinematics and dark matter halo spin in the ARTEMIS simulations

Abstract

We report a correlation between the presence of a Gaia-Sausage-Enceladus (GSE) analogue and dark matter halo spin in the ARTEMIS simulations of Milky Way-like galaxies. The haloes which contain a large population of accreted stars on highly radial orbits (like the GSE) have lower spin on average than their counterparts with more isotropic stellar velocity distributions. The median modified spin parameters ${\lambda }^{\prime }$ differ by a factor of $\sim 1.7$ at the present-day, with a similar value when the haloes far from virial equilibrium are removed. We also show that accreted stars make up a smaller proportion of the stellar populations in haloes containing a GSE analogue, and are stripped from satellites with stellar masses typically $\sim 4$ times smaller. Our findings suggest that the higher spin of DM haloes without a GSE-like feature is due to mergers with large satellites of stellar mass $\sim 10^{10}{M}_{\odot }$, which do not result in prominent radially anisotropic features like the GSE.

6 pages, 5 figures, accepted for publication by MNRAS Letters

References in corpus (7)

• The Gaia mission
• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• The total stellar halo mass of the Milky Way
• Do Mergers Spin up Dark Matter Halos?
• Merger-induced galaxy transformations in the ARTEMIS simulations
• A first estimate of the Milky Way dark matter halo spin

Cited by in corpus (1)

• Taking the Milky Way for a spin: disc formation in the ARTEMIS simulations