Long-term (250 yr) Hydrodynamical Simulation of the Supermassive Black Hole Binary OJ 287

Abstract With upcoming facilities capable of detecting photometric and gravitational wave signals from supermassive black hole (SMBH) binaries, studying their long-term accretion-driven variability is timely. OJ 287 is a bright, nearby ( z = 0.3), and well-studied candidate for an SMBH binary. As such, it is an excellent case study for how binary dynamics could influence observed active galactic nucleus photometric variability. We present 3D hydrodynamic simulations of OJ 287, using the code phantom . We simulate two mass ratios, (i) M 1 = 1.835 × 10 10 M ⊙ with M 2 = 1.4 × 10 8 M ⊙ and (ii) M 1 ≈ M 2 (∼10 8 M ⊙ ), along with (iii) a control of a single SMBH and accretion disk. We find that the simulation with masses 1.835 × 10 10 M ⊙ and 1.4 × 10 8 M ⊙ evolves consistently with the most currently accepted model of OJ 287 as a precessing SMBH binary. The secondary’s impacts with the disk result in the formation of spiral density waves and a corresponding ∼10%–20% increase in the mass accretion rate of the primary SMBH. The impact timings and the mass accretion rate spikes show quasiperiodic variability as a result of the precession of the secondary’s orbit with intervals between impacts ranging from ∼1 to ∼10 yr. In the near-equal mass case, the disk of the primary becomes tidally disrupted after ∼2 yr. Consequently, the near-equal mass system with a period of 12 yr is not a viable candidate for OJ 287. This modeling provides insights into the potential signatures of SMBH binaries by both gravitational wave observatories and the Rubin Legacy Survey of Space and Time.