A Chemical Evolution Model for the Fornax Dwarf Spheroidal Galaxy

TL;DR

This paper develops a chemical evolution model for the Fornax dwarf galaxy, linking star formation history with gas dynamics and supernova enrichment to understand its chemical evolution.

Contribution

It introduces a 2D chemical evolution model incorporating supernova ejecta mixing and gas flows, tailored for the Fornax galaxy's specific history.

Findings

Supernova ejecta mixing depends on the mass M_x, varying over time.

Global gas outflows can cause supernova ejecta to escape from Fornax.

Model results align with observed chemical abundance data.

Abstract

Fornax is the brightest Milky Way (MW) dwarf spheroidal galaxy and its star formation history (SFH) has been derived from observations. We estimate the time evolution of its gas mass and net inflow and outflow rates from the SFH using a simple star formation law that relates the star formation rate to the gas mass. We present a chemical evolution model on a 2D mass grid with supernovae (SNe) as sources of metal enrichment. We find that a key parameter controlling the enrichment is the mass M_x of the gas to mix with the ejecta from each SN. The choice of M_x depends on the evolution of SN remnants and on the global gas dynamics. It differs between the two types of SNe involved and between the periods before and after Fornax became an MW satellite at time t = t_sat . Our results indicate that due to the global gas outflow at t > t_sat , part of the ejecta from each SN may directly escape from Fornax. Sample results from our model are presented and compared with data.