About the Chemical Evolution of dSphs (and the peculiar Globular Cluster Omega Cen)

TL;DR

This study uses 3D hydrodynamical simulations to explore the chemical and dynamical evolution of dwarf spheroidal galaxies and their connection to peculiar globular clusters like Omega Cen, highlighting supernova-driven enrichment and multiple stellar populations.

Contribution

It introduces a novel inhomogeneous pollution model accounting for SNe Ia contributions, explaining observed chemical properties and stellar populations in dSphs and Omega Cen.

Findings

Reproduces the metallicity distribution function of dSphs.

Predicts two stellar populations with anti-correlated [Fe/H] and velocity dispersion.

Explains peculiar chemical properties of Omega Cen as a former dSph remnant.

Abstract

We present three dimensional hydrodynamical simulations aimed at studying the dynamical and chemical evolution of the interstellar medium (ISM) in isolated dwarf spheroidal galaxies (dSphs). This evolution is driven by the explosion of Type II and Type Ia supernovae, whose different contribution on both the dynamics and chemical enrichment is taken into account. Radiative losses are effective in radiating away the huge amount of energy released by SNe explosions, and the dSph is able to retain most of the gas allowing a long period (>2-3 Gyr) of star formation, as usually observed in this kind of galaxies. We are able to reproduce the stellar metallicity distribution function (MDF) as well as the peculiar chemical properties of strongly O-depleted stars observed in several dSphs. The model also naturally predicts two different stellar populations, with an anti-correlation between [Fe/H] and velocity dispersion, similarly to what observed in the Sculptor and Fornax dSphs. These results derive from the inhomogeneous pollution of the SNe Ia, a distinctive characteristic of our model. We also applied the model to the peculiar globular cluster (GC) Omega Cen in the hypothesis that it is the remnant of a formerly larger stellar system, possibly a dSph.