Title: Probing the Physics of the early Universe with Pulsating Stars
Speaker: Earl Bellinger (Yale)
Abstract:
The dawn of the universe left behind relics that persist to this day, from the oldest low-mass stars hiding in our Galactic halo to the seeds of the earliest supermassive black holes. Unearthing these fossils requires confronting the deluge of big observational data from missions like Kepler, TESS, and JWST with "big theoretical data" generated by simulations like MESA, GYRE, and FIRE. In this talk, I will present recent results from the Yale Astro Machine Learning (YAML) group, and demonstrate how we use pulsating stars to constrain the physics of the early cosmos. I will discuss the search for the first generation of stars, and show that asteroseismology, the study of stellar pulsations, is uniquely capable of revealing their primordial nature. I will also introduce our new models of time-dependent convection in MESA, which we use to characterize the variable stars that probe the Milky Way's dwarf galaxies. Finally, I will extend this analysis to the high-redshift universe, where JWST has recently uncovered a population of compact, red objects ("Little Red Dots"). Using our new code, MESA-QUEST, I will demonstrate that these objects are consistent with "quasi-stars": massive envelopes powered by the accretion of a central direct-collapse black hole. By analyzing the evolution and pulsations of these objects, I will show that we may have finally unearthed the origin of the first supermassive black holes.