The chemical case for no winds in dwarf irregular galaxies

TL;DR

This study demonstrates that isolated gas-rich dwarf irregular galaxies can be explained by chemo-photometric infall models with continuous star formation and no gas or metal loss, challenging the necessity of winds.

Contribution

It introduces a grid of chemo-photometric models that successfully reproduce observed properties of dwarf irregular galaxies without requiring gas or metal outflows.

Findings

Models with moderate to low star formation efficiency match observed abundances.

The models reproduce stellar and gas masses, colors, and elemental ratios.

External environmental effects are not necessary to explain these galaxies.

Abstract

We argue that isolated gas-rich dwarf galaxies -- in particular, dwarf irregular (dIrr) galaxies -- do not necessarily undergo significant gas loss. Our aim is to investigate whether the observed properties of isolated, gas-rich dwarf galaxies, not affected by external environmental processes, can be reproduced by self-consistent chemo-photometric infall models with continuous star formation histories and no mass or metals loss. The model is characterized by the total mass of primordial gas available to the object, its characteristic collapse timescale, and a constant star formation efficiency. A grid of 144 such models has been computed by varying these parameters, and their predictions (elemental abundances, stellar and gas masses, photometric colors) have been compared with a set of observations of dIrr galaxies obtained from the literature. It is found that the models with moderate to low efficiency are able to reproduce most of the observational data, including the relative abundances of nitrogen and oxygen.