Fig. 5: X-ray luminosity evolution of OGLE16aaa modeled with the tidal disruption by binary black hole.

a The observed 0.3–2 keV luminosity of OGLE16aaa at different epochs, shown with blue symbols. Error bars correspond to 1σ uncertainties, as that shown in Fig. 1. The 3σ upper limits are adopted for X-ray non-detections and shown with downward pointing arrows. Simulated light curve is shown in gray dot-dashed line, for the tidal disruption by binary black hole in the observer frame for OGLE16aaa (Table 3). As there is a time difference between the fallback particles and radiation in simulations, which is 40 days from the best-fit, the observed light curve is shifted rightward to match the simulated one. The magenta-red dotted line represents the canonical t^−5/3 decay law. Observational data are from Table 1. The horizontal thick lines represent different stages of X-ray evolution, as illustrated in b. b A schematic illustration of the evolution of X-ray emission. E1: The X-ray emission from the inner accretion disk of primary BH is initially obscured by a thick reprocessing layer, by which the X-ray radiation is absorbed and re-emitted at UV/optical wavelengths; E2: Ionization radiation results in a change in the opacity at later times, and direct escape of X-ray radiation (flare I). The reprocessing layer recedes inwards as \(\tau \mathop{ \sim }\limits^{<}1\); E3: Due to the perturbation of secondary BH, the infalling stream debris misses the accretion radius, causing interruptions in the light curve (dip I); E4: The accretion continues and X-ray flare occurs (flare II); E5: The infalling debris begins to miss again (dip II); E6: Beginning of another stage with accretion (flare III).