Date: Wednesday 06-Nov-2024
Time: 11:30-12:30 pm
Location: PSC 1136
Speaker: Madeline Lucey (University of Pennsylvania)
Title: The Galactic Halo's Contribution to Inner Galaxy Stellar Populations
Abstract: ΛCDM cosmology predicts the hierarchical formation of galaxies, with mass building up through merger events and the accretion of smaller systems. In the innermost regions, where dynamical times are relatively short, the phase-mixed stellar populations are thought to trace the Galaxy’s cumulative accretion history. Observations indicate that most of the stellar mass in the inner Galaxy is metal-rich, participating in the Galactic bar and forming a corresponding boxy/peanut-shaped (B/P) bulge. However, about ~5% of the stellar mass consists of metal-poor stars whose dynamical structure remains a topic of debate. In this talk, I will discuss my work from the Chemodynamical Origins of Metal-Poor Bulge Stars (COMBS) survey, demonstrating that at least half of the metal-poor stars in the inner Galaxy are halo stars on orbits with apocenters > 3.5 kpc, providing no evidence for a classical bulge in the Milky Way. Additionally, I will present my work using the FIRE-2 and Auriga cosmological zoom-in simulation suites of Milky Way-mass galaxies. I find that the stellar density profiles along the minor axis are not significantly correlated with metrics of the galaxy's accretion history, but are instead strongly correlated with the dark matter profile. Across simulation suites, the galaxies have a stellar-to-dark matter mass ratio that decreases as 1/R^2 along the minor axis. Whether these findings align with or challenge Milky Way observations remains to be determined.
Guidelines and format for the CTC Lunch seminars.
Past CTC Lunch seminars.
For other questions, contact the CTC Lunch host: Matt Nixon
SPECIAL ACCOMMODATIONS:
Special accommodations for individuals with disabilities can be made by calling (301) 405-3001. It would be appreciated if we are notified at least one week in advance.
