Apostle--Auriga: Effects of stellar feedback subgrid models on the evolution of angular momentum in disc galaxies

TL;DR

This study compares the effects of different stellar feedback models on the angular momentum evolution of disc galaxies using the Apostle and Auriga simulations, revealing that feedback implementation significantly influences galaxy angular momentum.

Contribution

It demonstrates how variations in stellar feedback subgrid models impact the angular momentum growth in simulated disc galaxies, highlighting the role of galactic fountains and CGM interactions.

Findings

Auriga galaxies have higher specific angular momentum at z=0.

Recycled fountain gas contributes significantly to angular momentum in Auriga.

Differences in feedback models affect gas recycling and angular momentum acquisition.

Abstract

Utilizing the Apostle--Auriga simulations, which start from the same zoom-in initial conditions of Local Group-like systems but run with different galaxy formation subgrid models and hydrodynamic solvers, we study the impact of stellar feedback models on the evolution of angular momentum in disc galaxies. At $z = 0$, Auriga disc galaxies tend to exhibit higher specific angular momenta compared to their cross-matched Apostle counterparts. By tracing the evolution history of the Lagrangian mass tracers of the in-situ star particles in the $z = 0$ galaxies, we find that the specific angular momentum distributions of the gas tracers from the two simulations at the halo accretion time are relatively similar. The present-day angular momentum difference is mainly driven by the physical processes occurring inside dark matter haloes, especially galactic fountains. Due to the different subgrid implementations of stellar feedback processes, Auriga galaxies contain a high fraction of gas that has gone through recycled fountain (${\sim} 65$ per cent) which could acquire angular momentum through mixing with the high angular momentum circumgalactic medium (CGM). In Apostle, however, the fraction of gas that has undergone the recycled fountain process is significantly lower (down to ${\sim} 20$ per cent for Milky Way-sized galaxies) and the angular momentum acquisition from the CGM is marginal. As a result, the present-day Auriga galaxies overall have higher specific angular momenta.