Orbit Tomography of Binary Supermassive Black Holes with Very Long Baseline Interferometry

Abstract In this work, we study how to infer the orbit of a supermassive black hole binary (SMBHB) by time-dependent measurements with very long baseline interferometry, such as Event Horizon Telescope (EHT). Assuming pointlike luminosity image model, show that multiple years observations EHT, it is possible recover SMBHB orbital parameters—eccentricity, (rescaled) semimajor axis, frequency, and angles—from their time-varying visibilities even if binaries’ periods are few times longer than duration observation. Together future gravitational wave detections resolved sources SMBHBs pulsar timing array, and/or optical-band light curves, will be able further measure individual mass binary, also determine Hubble constant total measured through curves two holes or alternative methods.