Near Field Cosmology with Milky Way's Satellite Galaxies and Stellar Streams

点击翻译按钮获取中文摘要

The Milky Way's outer halo is one of the best places in the Universe to learn about the formation and evolution of galaxies and the nature of the dark matter. In particular, the intact (e.g. dwarf galaxies, globular clusters) and disrupted (e.g. stellar streams) companions of the Milky Way become extremely powerful probes when positions, velocities, chemical abundances of individual stars in these systems are provided by the recent space-based (e.g. Gaia) and ground-based (e.g. Dark Energy Survey, Dark Energy Spectroscopic Instrument) surveys. By analyzing these datasets, we will be able to understand the building blocks of the Milky Way's stellar halo, the formation and evolution of the least massive galaxies, the mass and shape of the Milky Way's halo, and ultimately, the microscopic properties of dark matter (e.g. particle mass, cross-section, etc.). The long-term goal of my research program is to explore the foremost open questions in near-field cosmology. This proposal will focus on the following two Research Thrusts. First, we will analyze the data from the Southern Stellar Stream Spectroscopic Survey -- a survey I initiated in 2018 with a group of ~40 members -- to pursue a systematic study of 20+ stellar streams in 6D phase space; we will use this unique sample to not only constrain the mass of the Milky Way's dark matter halo, but also probe the progenitors and formation of the Milky Way's stellar halo. Second, we will analyze the spectroscopic data on the least luminous satellite systems of the Milky Way (i.e. ultra-faint dwarf galaxies and outer halo star clusters) with world's largest optical telescopes (e.g. Magellan, Very Large Telescope, Keck, etc.); we will determine the dynamical mass, orbital history, and the chemical signatures of these systems, understanding the difference in the formation and evolution of the smallest galaxies and smallest star clusters, as well as putting the tightest constraints on dark matter properties.