13 November: Connor Byrne

Speaker: Connor Byrne (Warwick)

Date: Wednesday 13 November 2024

Time: 15:00

Location: Physics 3.29

Chemical evolution and binary stars: Implications for the distant Universe

The James Webb Space Telescope (JWST) is providing tremendous insight into the high-redshift Universe, providing a detailed view of the earliest galaxies and allowing us to explore the nature of star and galaxy formation in the first billion years after the Big Bang. The stellar light from these galaxies is dominated by young stars which are preferentially enriched in oxygen over iron, since the formation of iron takes place over longer timescales. This poses a challenge for interpreting these galaxies with stellar population models, since models typically scale metallicity uniformly from the Solar composition. Another feature of these populations is they have a significant fraction of binary stars. Binary interactions change the appearance of a stellar population in a variety of ways and are more complex to model than a population of isolated, single stars. One model which is well equipped to explore this is BPASS (Binary Population and Spectral Synthesis) which combines detailed binary evolution models with libraries of stellar spectra to predict the integrated light of a stellar population for a wide variety of ages, compositions and star formation histories. Recent developments have focused on non-uniform scaling of metal abundances to better match the conditions in the distant Universe. In this talk, I will explore the impacts that these different abundance patterns have on the integrated light of the stellar population, and the overall evolution of the individual stars. I will highlight the uncertainties that this introduces into our interpretation of distant galaxies and outline the ongoing efforts being made to improve our models to better match the conditions found in the early Universe.