Tracing Ancient Mergers in the Heart of the Milky Way: RR Lyrae Stars and the Gaia-Enceladus/Sausage in the Inner Stellar Halo

Kunder et al. study RR Lyrae stars in the Milky Way’s inner halo to trace remnants of the ancient Gaia-Enceladus/Sausage merger. They find about 6-9% of these stars show motions and metallicities consistent with GES, less than in the solar neighborhood. Their results match simulations showing GES debris is less concentrated near the Galactic center.