Dottorato - PhD thesis
Area Tematica: RSN 2: Stelle, popolazioni stellari e mezzo interstellare
Referente: Emanuele Spitoni (
Titolo: Chemical Evolution of Local Group dSph and dIrr galaxies: Signatures of Interaction with the Milky Way
Decorrenza: 01.06.2025
Understanding the chemical evolution of dwarf irregular (dIrr) and dwarf spheroidal (dSph) in the Local Group is crucial to reconstructing the processes that shape small galaxy systems and their role in the evolution of the Milky Way. This PhD project will focus on the detailed modeling of the chemical evolution of selected dIrr and dSph galaxies, with a particular emphasis on those that are or have been in interaction with the Milky Way. We will employ state-of-the-art chemical evolution models, including gas inflow, and outflow, as well as nucleosynthetic yields from low-, intermediate-, and high-mass stars. The models will be tightly constrained using recent high-precision determinations of the star formation histories (SFHs) derived from color-magnitude diagram (CMD) fitting techniques, based on deep photometric observations. For example, the Large Magellanic Cloud (LMC) is the nearest and most thoroughly studied irregular galaxy. Its most distinctive morphological features include an off-centered bar and a single prominent spiral arm—structures thought to have formed through tidal interactions and possibly sustained by continued gas accretion. Using data from the SMASH survey and CMD fitting techniques, it has been possible to estimate the SFH in specific regions of the LMC. Building on this, the proposed project will enable the mapping of chemical abundance patterns across different areas of the LMC. Naturally, this analysis will be extended to the Small Magellanic Cloud (SMC) as well. Regarding dwarf galaxies, particular attention will be given to Sagittarius, as its pericentric passages are believed to have influenced star formation activity in the solar neighborhood. To robustly explore the parameter space of our chemical evolution models and to quantify uncertainties, we will adopt a Bayesian framework. The inference will be performed using advanced Markov Chain Monte Carlo (MCMC) techniques, enabling us to derive posterior probability distributions for key model parameters such as star formation efficiency, infall timescales, and galactic wind strengths. A major goal of this project is to assess the influence of environmental effects—such as tidal interactions, ram pressure stripping, and gas accretion—from the Milky Way and other galaxies on the chemical enrichment histories of its satellite galaxies. By comparing model predictions with observed abundance patterns and SFHs, this work aims to shed light on the interplay between internal evolutionary processes and external perturbations in shaping the chemical evolution of low-mass galaxies in the Local Group.
