The chemical evolution of IC10

TL;DR

This study models the chemical evolution of dwarf galaxy IC10, revealing that metal-enhanced winds and bursty star formation best explain its observed properties, with a slow gas accretion over billions of years.

Contribution

It introduces detailed chemical evolution models for IC10 considering various wind and star formation scenarios, identifying the importance of metal-enhanced winds and bursty star formation.

Findings

Metal-enhanced winds are necessary to match IC10's properties.

Star formation occurred in bursts fewer than 10 times over its history.

IC10's gas accretion was a slow process over approximately 8 Gyr.

Abstract

Dwarf irregular galaxies are relatively simple unevolved objects where it is easy to test models of galactic chemical evolution. We attempt to determine the star formation and gas accretion history of IC10, a local dwarf irregular for which abundance, gas, and mass determinations are available. We apply detailed chemical evolution models to predict the evolution of several chemical elements (He, O, N, S) and compared our predictions with the observational data. We consider additional constraints such as the present-time gas fraction, the star formation rate (SFR), and the total estimated mass of IC10. We assume a dark matter halo for this galaxy and study the development of a galactic wind. We consider different star formation regimes: bursting and continuous. We explore different wind situations: i) normal wind, where all the gas is lost at the same rate and ii) metal-enhanced wind, where metals produced by supernovae are preferentially lost. We study a case without wind. We vary the star formation efficiency (SFE), the wind efficiency, and the time scale of the gas infall, which are the most important parameters in our models. We find that only models with metal-enhanced galactic winds can reproduce the properties of IC10. The star formation must have proceeded in bursts rather than continuously and the bursts must have been less numerous than ~10 over the whole galactic lifetime. Finally, IC10 must have formed by a slow process of gas accretion with a timescale of the order of 8 Gyr.