Accreting Binaries: From Brown Dwarfs to Major Mergers

From the collapse of molecular clouds into stars to spectacular galactic mergers, binary systems form on many scales across the universe. Interactions between binaries and their environments can sculpt the stellar populations we observe today, alter the spectrum of gravitational waves emitted by supermassive black hole pairs, and produce electromagnetic counterparts to black hole binary mergers. After providing a general overview of circumbinary accretion, I will review on some of my own recent work. Topics will include accretion onto supermassive black hole binaries as they traverse the LISA band, and the early evolution of stellar-mass black hole binaries in AGN disks.