Chemo-dynamical Evolution of Simulated Satellites for a Milky Way-like Galaxy

TL;DR

This study uses high-resolution simulations to connect chemical abundances in satellite galaxies with their star formation histories, predicting that upcoming surveys will reveal episodic star formation through chemical signatures.

Contribution

It provides a detailed simulation-based analysis of satellite galaxy evolution, linking chemical abundances to star formation episodes and forecasting observational capabilities of future spectroscopic surveys.

Findings

Star formation in satellites is often quenched before infall.

Star formation episodes are separated by a few hundred Myr due to feedback.

Upcoming Subaru PFS will detect distinct chemical groups indicating episodic SFHs.

Abstract

The chemical abundances of Milky Way's satellites reflect their star formation histories (SFHs), yet, due to the difficulty of determining the ages of old stars, the SFHs of most satellites are poorly measured. Ongoing and upcoming surveys will obtain around ten times more medium-resolution spectra for stars in satellites than are currently available. To correctly extract SFHs from large samples of chemical abundances, the relationship between chemical abundances and SFHs needs to be clarified. Here, we perform a high-resolution cosmological zoom-in simulation of a Milky Way-like galaxy with detailed models of star formation, supernova feedback, and metal diffusion. We quantify SFHs, metallicity distribution functions, and the $\alpha$-element (Mg, Ca, and Si) abundances in satellites of the host galaxy. We find that star formation in most simulated satellites is quenched before infalling to their host. Star formation episodes in simulated satellites are separated by a few hundred Myr owing to supernova feedback; each star formation event produces groups of stars with similar [$\alpha$/Fe] and [Fe/H]. We then perform a mock observation of the upcoming Subaru Prime Focus Spectrograph (PFS) observations. We find that Subaru PFS will be able to detect distinct groups of stars in [$\alpha$/Fe] vs. [Fe/H] space, produced by episodic star formation. This result means that episodic SFHs can be estimated from the chemical abundances of $\gtrsim$ 1,000 stars determined with medium-resolution spectroscopy.