Learning the Universe: GalactISM simulations of resolved star formation and galactic outflows across main sequence and quenched galactic environments

TL;DR

This paper presents high-resolution simulations of galaxies in different environments, revealing how galactic rotation influences star formation, feedback, and outflow properties, with implications for modeling galaxy evolution.

Contribution

It introduces a suite of chemo-dynamical simulations that connect galactic rotation to star formation regulation and feedback processes in diverse galaxy types.

Findings

Outflow mass-loading is linked to supernova clustering and galactic rotation.

Bulge-dominated galaxies have higher gas densities and molecular fractions.

Star formation rate is mostly pressure-regulated, with suppression in high-rotation bulges.

Abstract

We present a suite of six high-resolution chemo-dynamical simulations of isolated galaxies, spanning observed disk-dominated environments on the star-forming main sequence, as well as quenched, bulge-dominated environments. We compare and contrast the physics driving star formation and stellar feedback amongst the galaxies, with a view to modeling these processes in cosmological simulations. We find that the mass-loading of galactic outflows is coupled to the clustering of supernova explosions, which varies strongly with the rate of galactic rotation $\Omega = v_c/R$ via the Toomre length, leading to smoother gas disks in the bulge-dominated galaxies. This sets an equation of state in the star-forming gas that also varies strongly with $\Omega$, so that the bulge-dominated galaxies have higher mid-plane densities, lower velocity dispersions, and higher molecular gas fractions than their main sequence counterparts. The star formation rate in five out of six galaxies is independent of $\Omega$, and is consistent with regulation by the mid-plane gas pressure alone. In the sixth galaxy, which has the most centrally-concentrated bulge and thus the highest $\Omega$, we reproduce dynamical suppression of the star formation efficiency (SFE) in agreement with observations. This produces a transition away from pressure-regulated star formation.