The Milky Way's progenitor experienced several merger events which left their imprints on the stellar halo, including the Gaia-Sausage/Enceladus. Recently, it has been proposed that this event perturbed the proto-disk and gave rise to a metal rich ([Fe/H] >−1) low angular momentum (vϕ<100 km/s) stellar population. These stars have dynamical and chemical properties different from the accreted stellar halo, but are continuous with the canonical thick disk. In this letter, we use a hydrodynamical simulation of an isolated galaxy which develops clumps that produce a bimodal thin+thick disk chemistry to explore whether it forms such a population. We demonstrate clump scattering forms a metal-rich, low angular momentum population, without the need for a major merger. We show that, in the simulation, these stars have chemistry, kinematics and density distribution in good agreement with those in the Milky Way.
@article{arxiv.1912.12690,
title = {The Splash without a merger},
author = {João A. S. Amarante and Leandro Beraldo e Silva and Victor P. Debattista and Martin C. Smith},
journal= {arXiv preprint arXiv:1912.12690},
year = {2020}
}