Three-dimensional hydrodynamical simulations of the supernovae-driven gas loss in the dwarf spheroidal galaxy Ursa Minor

TL;DR

This study uses three-dimensional hydrodynamical simulations to investigate how supernova-driven winds contributed to gas loss in the dwarf galaxy Ursa Minor, revealing the importance of supernova rates and initial gas density.

Contribution

First 3D hydrodynamical simulations of Ursa Minor's gas loss driven solely by supernovae, linking star formation history to gas removal mechanisms.

Findings

Higher supernova rates increase gas removal efficiency.

Lower initial gas density leads to more effective gas loss.

Gas loss is more significant in the central 300 pc region.

Abstract

As is usual in dwarf spheroidal galaxies, today the Local Group galaxy Ursa Minor is depleted of its gas content. How this galaxy lost its gas is still a matter of debate. To study the history of gas loss in Ursa Minor, we conducted the first three-dimensional hydrodynamical simulations of this object, assuming that the gas loss was driven by galactic winds powered only by type II supernovae (SNe II). The initial gas setup and supernova (SN) rates used in our simulations are mainly constrained by the inferred star formation history and the observed velocity dispersion of Ursa Minor. After 3 Gyr of evolution, we found that the gas removal efficiency is higher when the SN rate is increased, and also when the initial mean gas density is lowered. The derived mass-loss rates are systematically higher in the central regions (<300 pc), even though such a relationship has not been strictly linear in time and in terms of the galactic radius. The filamentary structures induced by Rayleigh-Taylor instabilities and the concentric shells related to the acoustic waves driven by SNe can account for the inferred mass losses from the simulations. Our results suggest that SNe II are able to transfer most of the gas from the central region outward to the galactic halo. However, other physical mechanisms must be considered in order to completely remove the gas at larger radii.