Key points are not available for this paper at this time.
The Gaia-Sausage-Enceladus merger was a major event in the history of the Milky Way. Studies on Milky Way satellite dwarf galaxies show that key elemental abundance patterns, which probe different nucleosynthetic channels, reflect the host galaxy's star formation history. We gather Mg, Fe, Ba, and Eu abundance measurements for Gaia-Sausage-Enceladus stars from the SAGA database and use Fe/Mg, Ba/Mg, Eu/Mg, and Eu/Ba, as a function of Fe/H to constrain the star formation history of Gaia-Sausage-Enceladus. We use the known star formation histories and elemental abundance patterns of the Sculptor and Fornax dwarf spheroidal galaxies as comparison. The elemental abundance ratios of Fe/Mg, Ba/Mg, Eu/Mg, and Eu/Ba all increase with Fe/H in Gaia-Sausage- Enceladus. The Eu/Mg begins to increase at Fe/H= -2.0 and continues steadily, contrasting with the Sculptor dSph galaxy. The Eu/Ba increases and remains high across the Fe/H range, contrasting with that of the Sculptor dSph galaxy and deviating from the Fornax dSph galaxy at high Fe/H. The Ba/Mg is higher than those of the Sculptor dSph galaxy at the lowest Fe/H and gradually increases, similar to the Fornax dSph galaxy. We constrain three main properties of the Gaia-Sausage-Enceladus star formation history: 1) star formation started gradually, 2) it extended for over 2 Gyr, and 3) it was quenched around Fe/H of -0.5, likely when it fell into the Milky Way.
Ernandes et al. (Wed,) studied this question.