Exploring the evolution of a dwarf spheroidal galaxy with SPH simulations: I. Stellar feedback

TL;DR

This study uses SPH simulations to investigate how stellar feedback influences gas depletion and evolution in dwarf spheroidal galaxies, particularly Leo II, highlighting feedback's potential sufficiency in galaxy quenching.

Contribution

It demonstrates that stellar feedback alone can explain key properties of dwarf spheroidals, challenging the necessity of environmental effects for galaxy quenching.

Findings

Stellar feedback can cause recent star formation quenching.

Simulations match observed gas mass and stellar mass within tidal radius.

Discrepancies in stellar age and metallicity distributions suggest complex gas infall processes.

Abstract

A fundamental question regarding the evolution of dwarf spheroidal galaxies is the identification of the key physical mechanisms responsible for gas depletion. Here, we focus on the study of stellar feedback in isolated dwarf spheroidal galaxies, by performing numerical simulations using a modified version of the SPH code GADGET-3. The Milky Way satellite Leo II (PGC 34176) in the Local Group was considered as our default model dwarf galaxy. The parameter space for the stellar feedback models was explored to match observational constraints of Leo II, such as residual gas mass, total mass within the tidal radius, star formation history, final stellar mass, stellar ages and metallicity. Additionally, we examined the impact of the binary fraction of stars, initial mass function, dark matter halo mass and initial gas reservoir. Many simulations revealed recent star formation quenching due to stellar feedback. In general, the gas depletion, expected star formation history, total mass of stars and total mass within the tidal radius were adequately reproduced in the simulations when compared to observational estimates. However, there were discrepancies in the distribution of stellar ages and metallicities, which suggested that the cosmic gas infall would play a more complex role in our dwarf spheroidal galaxy than captured by a monolithic infall scenario. Our results suggest that currently quenched dwarf galaxies may not necessarily need to evolve within clusters or groups, and that stellar feedback alone could be a sufficient factor in shaping at least some of these galaxies as we observe them today.