Gaia-Sausage-Enceladus star formation history as revealed by detailed elemental abundances

TL;DR

This study uses detailed elemental abundance data to reconstruct the star formation history of Gaia-Sausage-Enceladus, revealing a prolonged, slow star formation period over 2 Gyr before its merger with the Milky Way.

Contribution

It provides the first detailed chemical evolution analysis of GSE using neutron capture elements, highlighting its extended star formation history compared to other dwarf galaxies.

Findings

GSE experienced over 2 Gyr of slow star formation.

Elemental abundance ratios indicate a quenching after merger.

GSE's chemical signatures differ from surviving satellites.

Abstract

The Gaia-Sausage-Enceladus was the last major merger and central turning point in the Milky Way's story. This event, comparable in mass to the Large Magellanic Cloud today, left behind significant debris that provides valuable insights into the assembly history of our Galaxy and the chemical evolution of dwarf galaxies. By examining the aftermath of the GSE merger, we can delve deeper into understanding how the Milky Way's formation unfolded and how dwarf galaxies evolved chemically. Specifically, the distinct patterns of neutron capture elements such as Eu and Ba, along with Mg, offer clues about the star formation history. Through a comprehensive analysis of data compiled in the SAGA database, we investigated the Gaia Sausage-Enceladus' star formation history. Elemental abundance ratios ([Eu/Mg], [Ba/Mg], and [Eu/Ba]) derived from this study, when compared with those of surviving Milky Way satellites, indicate that the GSE experienced a prolonged period of slow star formation, lasting over 2 Gyr, until it was eventually quenched by merging with the Milky Way. Consequently, these elemental signatures serve as a unique window into the complex history of both surviving and accreted satellites orbiting our Galaxy.