Title: Understanding the Galaxy-Halo Connection with HI Gas Kinematics
Speaker: Dilys Ruan (Rutgers)
Abstract: We still do not fully understand the nature of dark matter, and it remains difficult to distinguish between effects from dark matter models versus baryonic feedback (e.g., cusp versus core problem, diversity of rotation curves). Dwarf galaxies are dark matter-dominated and have shallow gravitational potential wells, and are therefore ideal laboratories to study dark matter + gas physics in tandem. My research focuses on connecting the galaxy's dark matter halo to the gas disk, which primarily consists of neutral hydrogen (HI), and predicting constraints for observations. I utilize the N-Body Shop's Marvel-ous and Marvelous Massive Dwarfs smoothed particle hydrodynamics + N-body simulation sets, and study a sample of 66 dwarf galaxies with Mstar=10^6-10^9 Msol and realistic HI properties. In this talk, I will share my work on the baryonic Tully Fisher Relation (“bTFR”, typically a power-law relation between baryonic mass vs rotation velocity). Due to inefficient galaxy formation at lower masses, we find a turndown in the bTFR at Mbary<10^8.5 Msol, or ~50 km/s. After comparing different observationally-oriented HI velocity definitions, we determine that the only way to measure a turndown in the bTFR is with spatially resolved observations at an HI surface density limit < 0.08 Msol/pc^2, which is already being achieved by surveys like FEASTS and MHONGOOSE. In the remaining time, I will highlight my other (preliminary) work which compares HI profiles between dark matter models (CDM and SIDM) and implications for galaxy support (dispersion versus rotation) and size.