Influence of the Gaia–Sausage–Enceladus on the Density Shape of the Galactic Stellar Halo Revealed by Halo K Giants from the LAMOST Survey

作者：Wenbo Wu, Gang Zhao, Xiang-Xiang Xue, Wenxiang Pei, Chengqun Yang · 发表于：The Astronomical Journal · 年份：2022 · DOI：10.3847/1538-3881/ac746e · 被引用次数：11 · 研究领域：Stellar, planetary, and galactic studies、Gamma-ray bursts and supernovae、Astrophysics and Star Formation Studies

Abstract We present a study of the influence of the Gaia–Sausage–Enceladus (GSE) on the density shape of the Galactic stellar halo using 11,624 K giants from the LAMOST survey. Every star is assigned a probability of being a member of the GSE based on its spherical velocities and metallicity by a Gaussian mixture model. We divide the stellar halo into two parts by the obtained probabilities, of which one is composed of the GSE members and defined as the GSE-related halo, and the other one is referred to as the GSE-removed halo. Using a nonparametric method, the radial number density profiles of the two stellar halos can be well described by a single power law with a variable flattening q ( r = R 2 + ( Z / q ( r ) ) 2 , ν = ν 0 r − α ). The index α is 4.92 ± 0.12 for the GSE-related halo and 4.25 ± 0.14 for the GSE-removed halo. Both of the stellar halos are vertically flattened at smaller radii but become more spherical at larger radii. We find that the GSE-related halo is less vertically flattened than the GSE-removed halo, and the difference of q between the two stellar halos ranges from 0.07 to 0.15. However, after the consideration of the bias, it is thought to be within 0.08 at most of the radii. Finally, we compare our results with two Milky Way analogs that experience a significant major merger in the TNG50 simulation. The study of the two analogs also sh...