Dual Effects of Ram Pressure on Star Formation in Multi-phase Disk Galaxies with Strong Stellar Feedback

TL;DR

This study uses radiation-hydrodynamics simulations to explore how ram pressure from the intracluster medium can both trigger and suppress star formation in multi-phase disk galaxies with strong stellar feedback, depending on wind strength.

Contribution

It reveals the dual effects of ram pressure on star formation, showing both enhancement and suppression mechanisms in different galactic regions and wind conditions.

Findings

Moderate winds increase star formation rates by up to 80%.

Strong winds rapidly strip gas and suppress star formation by a factor of two.

Dense gas clumps form in extraplanar regions but do not lead to significant new stars.

Abstract

We investigate the impact of ram pressure stripping due to the intracluster medium (ICM) on star-forming disk galaxies with a multi-phase interstellar medium (ISM) maintained by strong stellar feedback. We carry out radiation-hydrodynamics simulations of an isolated disk galaxy embedded in a 10^11 Msun dark matter halo with various ICM winds mimicking the cluster outskirts (moderate) and the central environment (strong). We find that both star formation quenching and triggering occur in ram pressure-stripped galaxies, depending on the strength of the winds. HI and H$_2$ in the outer galactic disk are significantly stripped in the presence of the moderate winds, whereas turbulent pressure provides support against ram pressure in the central region where star formation is active. Moderate ICM winds facilitate gas collapsing, increasing the total star formation rates by ~40% when the wind is oriented face-on or ~80% when it is edge-on. In contrast, strong winds rapidly blow away neutral and molecular hydrogen gas from the galaxy, suppressing the star formation by a factor of two within ~200 Myr. Dense gas clumps with N_H > 10 Msun pc^-2 are easily identified in extraplanar regions, but no significant young stellar populations are found in such clumps. In our attempts to enhance radiative cooling by adopting a colder ICM of T=10^6K, only a few additional stars are formed in the tail region, even if the amount of newly cooled gas increases by an order of magnitude.