Relativistic binary-disc dynamics and the timing of OJ-287’s flares

Abstract

We revisit the precessing black hole binary model, a candidate to explain the bizarre quasi-periodic optical flares in OJ-287’s light curve, from first principles. We deviate from existing work in three significant ways: (1) Including crucial aspects of relativistic dynamics related to the accretion disc’s gravitational moments. (2) Adopting a model-agnostic prescription for the disc’s density and scale height. (3) Using Markov chain Monte Carlo methods to recover reliable system parameters and uncertainties. We showcase our model’s predictive power by timing the 2019 Eddington flare within 40 h of the observed epoch, exclusively using data available prior to it. Additionally, we obtain a novel direct measurement of OJ-287’s disc mass and quadrupole moment exclusively from the optical flare timings. Our improved methodology can uncover previously unstated correlations in the parameter posteriors and patterns in the flare timing uncertainties. According to the model, the 26th optical flare is expected to occur on the 21st of August 2023 ± 32 d, shifted by approximately a year with respect to previous expectations.