Multi-band light curves from eccentric accreting supermassive black hole binaries

We use long-run, high-resolution hydrodynamics simulations to compute the multi-wavelength light curves (LCs) from thermal disk emission around accreting equal-mass supermassive black hole (BH) binaries, with a focus on revealing binary eccentricity. LCs are obtained by modeling the disk thermodynamics with an adiabatic equation of state, a local blackbody cooling prescription, and corrections to approximate the effects of radiation pressure. We find that in general, the optical and infrared LCs are in-phase with one another (to within $\sim\,$2\% of an orbital period), but they contain pulse substructure in the time domain that is not necessarily reflected in BH accretion rates $\dot M$. We thus predict that multi-wavelength observing campaigns will reveal binary-hosting AGN to exhibit highly correlated, in-phase, periodic brightness modulations in their low-energy disk emission. If jet emission is predicted by $\dot{M}$, then we predict a weaker correlation with low-energy disk emission due to the differing sub-peak structure. We show that LC variability due to hydrodynamics likely dominates Doppler brightening for all equal-mass binaries with disk Mach numbers $\lesssim 20$. A promising signature of eccentricity is weak or absent ``lump'' periodicity. We find hints that $\dot{M}$ significantly lags the low-energy disk emission for circular binaries, but is in-phase for eccentric binaries, which might explain some ``orphan'' blazar flares with no $\gamma$-ray counterpart.