Multi-messenger Constraints on Close Binary Evolution in the Milky Way

The process of binary stellar evolution is a complex tapestry of initial stellar evolutionary parameters convolved with a lifetime of orbital and mass evolution that leave imprints in the observational properties of the large population of binaries in the Milky Way galaxy. Even beyond the conventional end of stellar life, when main sequence stars have evolved into stellar remnants, binary systems continue to evolve through interactions with their stellar-mass partner. The stellar graveyard of the Milky Way, comprised of highly evolved stars and stellar remnants, encodes a record of the physical processes that drive the evolution of these systems throughout their lives. Our current ability to probe and disentangle this evolutionary history is built on three interlinked probes of the population: electromagnetic surveys, numerical simulation and population synthesis, and forthcoming gravitational wave surveys. This proposal outlines a concerted effort to tightly link these three probes in a comprehensive multi-messenger observation program. We are specifically interested in how electromagnetic observations define the current boundaries of possible model inputs for population synthesis, how electromagnetic observations will quantitatively inform gravitational wave searches, how gravitational wave observations will seed electromagnetic follow-up (particularly in large-scale time-domain transient surveys), how joint EM-GW analyses of ultra-compact binaries can be conducted in the LISA era, and how joint EM-GW data will be used in model selection analyses to constrain binary evolution scenarios.