Simulations of Barred Galaxies in Triaxial Dark Matter Haloes: The Effects of Gas

TL;DR

This study uses hydrodynamical simulations to investigate how gas content and halo shape influence bar formation in disc galaxies, revealing that gas presence significantly weakens bars more than halo triaxiality.

Contribution

It introduces a comprehensive simulation approach to analyze the combined effects of gas and halo shape on galactic bar development, highlighting the dominant role of gas.

Findings

Gas content reduces bar strength in galaxies.

Halo triaxiality influences bar formation but less than gas.

All models converge to similar gas content after evolution.

Abstract

The baryonic discs of galaxies are believed to alter the shapes of the dark matter haloes in which they reside. We perform a set of hydrodynamical N-body simulations of disc galaxies with triaxial dark matter haloes, using elliptical discs with a gaseous component as initial conditions. We explore models of different halo triaxiality and also of different initial gas fractions, which allows us to evaluate how each affects the formations of the bar. Due to star formation, models of all halo shapes and of all initial gas fractions reach approximately the same gas content at the end of the simulation. Nevertheless, we find that the presence of gas in the early phases has important effects on the subsequent evolution. Bars are generally weaker for larger initial gas content and for larger halo triaxiality. The presence of gas, however, is a more efficient factor in inhibiting the formation of a strong bar than halo triaxiality is.