The Unique Blazar OJ 287 and Its Massive Binary Black Hole Central Engine

Abstract

The bright blazar OJ 287 is the best-known candidate for hosting a nanohertz gravitational wave (GW) emitting supermassive binary black hole (SMBBH) in the present observable universe. The binary black hole (BBH) central engine model, proposed by Lehto and Valtonen in 1996, was influenced by the two distinct periodicities inferred from the optical light curve of OJ 287. The current improved model employs an accurate general relativistic description to track the trajectory of the secondary black hole (BH) which is crucial to predict the inherent impact flares of OJ 287. The successful observations of three predicted impact flares open up the possibility of using this BBH system to test general relativity in a hitherto unexplored strong field regime. Additionally, we briefly describe an on-going effort to interpret observations of OJ 287 in a Bayesian framework.

The quest for dual and binary supermassive black holes: A multi-messenger view

“…From SMBHB candidates separated well below the resolution limits of radio interferometers, an extensively studied example is the blazar OJ 287. Its quasi-periodic optical light curve shows double peaks about every 12 yr (Sillanpaa et al, 1988); see also the recent review by Dey et al (2019). These variations have been explained in the context of a number of different binary SMBH scenarios.…”

“…The complex VLBI jet of OJ 287 has been described with a helical model (Valtonen and Pihajoki, 2013) in a way that is consistent with the binary orbital motion. Most recently, Britzen et al (2018) presented an extensive study of the jet emission of OJ 287 at cm wavelengths, combining VLBI and single-dish radio data, and found that precession of an accretion disk around a single SMBH can explain the observed periodic behaviour of the jet morphology and radio flux density changes (but not the optical long-term lightcurve and polarimetry; Dey et al 2019). A binary is still likely needed in that model for explaining the disk precession itself.…”

“…The most recent modelling of OJ 287 in the context of the SMBHB model of Valtonen and collaborators is based on 4.5 order post-Newtonian dynamics. It requires a binary of mass ratio q 0.01, a massive primary of 1.8 × 10 10 M , and an eccentric orbit of the secondary with = 0.7 (re-view by Dey et al 2019). The orbit is subject to General Relativity (GR) precession of the pericenter of ∆φ = 39 deg/orbit.…”

Spitzer Observations of the Predicted Eddington Flare from Blazar OJ 287

“…The binary black hole (BBH) central engine description for the bright blazar OJ287 provides the most promising scenario for the existence of a nano-Hz GW emitting massive BH binary (Dey et al 2019). The model naturally explains the observed double-peaked high brightness flares (outbursts) from OJ287 and predicts the arrival time of future outbursts.…”

Revisiting the 2PN Pericenter Precession in View of Possible Future Measurements

“…Our aim is revisiting the issue of analytically calculating the 2PN pericentre precession by straightforwardly computing it perturbatively with the widely known method of variation of the orbital elements (Tisserand 1889;Plummer 1960;Brouwer & Clemence 1961;Danby 1962;Soffel 1989;Brumberg 1991;Murray & Dermott 2000;Bertotti, Farinella & Vokrouhlický 2003;Roy 2005;Kopeikin, Efroimsky & Kaplan 2011;Poisson & Will 2014;Soffel & Han 2019) in order to provide quickly understandable formulas, ready to be used in practical calculations in view of possible measurements in a not so far future, more likely in binary pulsars than in our Solar system, or to better model the dynamics of peculiar systems like, e.g., tight extrasolar planetary systems or the BL Lac object OJ 287 (Dey et al 2018(Dey et al , 2019. A similar strategy was adopted in Kopeikin & Potapov (1994).…”