Binary black holes gone MAD: Magnetically arrested minidisks around nonspinning binary black holes

Modeling the electromagnetic signatures unique to supermassive binary black holes (SMBBHs) accreting magnetized gas is a major goal for multimessenger astronomy. Around single BHs, magnetized accretion flows often become magnetically arrested disks (MAD) that can power efficient jets, winds, and electromagnetic flaring in the infrared and X-ray. However, MADs have received little attention in SMBBH accretion. In this talk, I will present magnetohydrodynamic simulations in full 3+1 general relativity of circumbinary disk accretion onto nonspinning binary black holes that establish the formation of magnetically arrested minidisks (MAM). I will outline the key features that signify a MAM, and I will discuss the implications of MAMs for multimessenger astronomy with SMBBHs.