KIPAC Tea Talk: Metal-poor Massive Binaries and Binary Products In the Local Group

Abstract: Metal-poor massive stars are central to our understanding of the Universe. They dominate the light of star-forming galaxies at high-redshift and may give rise to explosive transients, including gravitational wave sources Yet, at metallicity below that of the Small Magellanic Cloud (SMC), they remain observationally poorly constrained, leading to uncertainties in their evolution and final fates. In this talk, I will showcase a novel use of data from JWST and HST imaging to identify and characterize metal-poor massive binaries aiming to tackle these uncertainties. The neural network approaches, panchromatic light-curve modeling, and data processing strategies I will discuss can be readily adapted for upcoming space-based photometry missions. I will highlight the discovery of the most metal-poor massive contact binary candidate known to date in WLM (~14% Zsun), along with additional short-period massive binary candidates in Local Group dwarf galaxies, which represents the first dedicated search for binaries at sub-SMC metallicity. Furthermore, I will present the lowest metallicity spectroscopic sample (~5%Zsun) of Be stars observed to date and comment on their properties and fraction as a trend with metallicity. Lastly, I will outline how observational data and theoretical models can be utilized to put constraints on the nature of future binary products and inform our understanding of massive stars across red-shifts.