May 7
Understanding star formation in the first billion years with flexible galaxy models
Speaker: Sahil Hegde, Grad Student, UCLA
Abstract: The quest to find the first stars has driven astronomers across cosmic time, from hopes to identify their signatures in their heyday at cosmic dawn to deep searches for their remnants in our local neighborhood. While these searches, which began in the Hubble era and have more recently been reinvigorated with JWST, have revealed a number of potential candidates, our observational understanding of early star formation remains incomplete. Building up a statistical sample to piece together this puzzle crucially relies on robust theoretical modelling to identify when and where we expect low-metallicity star formation to have occurred and survived. In this talk, I will describe our latest semi-analytic efforts to efficiently trace the formation of the first stars from their birth through the first billion years of our universe's history, jointly following star formation out of pristine and metal-enriched gas over time in a framework we call the “abcd” model. With abcd, we can bridge the gap between numerical simulations and previous semi-analytic models, self-consistently following star formation from the minihalo era through the epoch of reionization, finding that pristine star formation can persist at a high level even in the presence of Pop II star formation down to z~5, but is limited to the most massive halos. I will discuss the implications of these theoretical predictions for our observational landscape and touch on promising avenues to search for Pop III star formation through deep galaxy observations, transient searches, and intensity mapping measurements, suggesting that the first constraints on the demographics of the first stars could be within reach.
Host: Yash Gursahani