On the influence of ram-pressure stripping on the star formation of simulated spiral galaxies

TL;DR

This study uses simulations to show that ram-pressure stripping can significantly enhance star formation in spiral galaxies, creating extended stellar structures and 'stripped baryonic dwarf' galaxies, with results aligning with analytical estimates.

Contribution

It demonstrates the impact of ram-pressure stripping on star formation and galaxy morphology using combined N-body/hydrodynamic simulations, introducing the concept of 'stripped baryonic dwarf' galaxies.

Findings

Star formation rate increases up to three times due to ram-pressure

Stars form in compressed central regions and in stripped gas behind the galaxy

Analytical stripping radius estimates agree with simulation results

Abstract

We investigate the influence of ram-pressure stripping on the star formation and the mass distribution in simulated spiral galaxies. Special emphasis is put on the question where the newly formed stars are located. The stripping radius from the simulation is compared to analytical estimates. Disc galaxies are modelled in combined N-body/hydrodynamic simulations (GADGET-2) with prescriptions for cooling, star formation, stellar feedback, and galactic winds. These model galaxies move through a constant density and temperature gas, which has parameters comparable to the intra-cluster medium (ICM) in the outskirts of a galaxy cluster (T=3 keV ~3.6x10^7 K and rho=10^-28 g/cm^3). With this numerical setup we analyse the influence of ram-pressure stripping on the star formation rate of the model galaxy. We find that the star formation rate is significantly enhanced by the ram-pressure effect (up to a factor of 3). Stars form in the compressed central region of the galaxy as well as in the stripped gas behind the galaxy. Newly formed stars can be found up to hundred kpc behind the disc, forming structures with sizes of roughly 1 kpc in diameter and with masses of up to 10^7 M_sun. As they do not possess a dark matter halo due to their formation history, we name them 'stripped baryonic dwarf' galaxies. We also find that the analytical estimate for the stripping radius from a Gunn & Gott (1972) criterion is in good agreement with the numerical value from the simulation. Like in former investigations, edge-on systems lose less gas than face-on systems and the resulting spatial distribution of the gas and the newly formed stars is different.