The Angular Momentum of the Circumgalactic Medium in the TNG100 Simulation

Understand

We present an analysis of the angular momentum content of the circumgalactic medium (CGM) using TNG100, one of the flagship runs of the IllustrisTNG project.

• We focus on Milky Way-mass halos ($\sim 10^{12} \; M_{\odot}$) at $z=0$ but also analyze other masses and redshifts up to $z=5$.
• We find that the CGM angular momentum properties are strongly correlated with the stellar angular momentum of the corresponding galaxy: the CGM surrounding high-angular momentum galaxies has a systematically higher angular momentum and is better aligned to the rotational axis of the galaxy itself than the CGM surrounding low-angular momentum galaxies.
• Both the hot and cold phases of the CGM show this dichotomy, though it is stronger for colder gas.