I will review the status of theoretical modeling of magnetized circumbinary accretion disks when the SMBH binary is inspiraling and coalescing due to the emission of Gravitational Waves. I report results from simulations in General Relativity of magnetized disks accreting onto orbiting, inspiraling and merging black hole binaries. The results are contrasted with simulations of the same initial disk around a single, non-spinning black hole. The simulations feature an effective, rapid radiative cooling scheme as a limiting case of future treatments with radiative transfer. The importance of magnetic fields, potential implications of radiative cooling, and the dependence on binary mass ratio will be shown. The multimessenger aspect of these sources is shown by the computed gravitational waveforms and estimates for various forms of possible outgoing radiation. Promising, time-dependent signatures during inspiral and near merger are discussed. The presentation will include visualizations that highlight the presence of incipient jets throughout the evolution in all binary cases considered. Such jets are not observed nor expected in simulations with the same initial disk accreting onto a single non-spinning black hole. Potential implications and prospects for an observational identification of similar systems based on electromagnetic signatures will be discussed and key directions to improve predictions from theoretical models will be listed.
Roman Gold
