Date Presented:

2017/06/1

Abstract:

The presence of a supermassive binary black hole (BBH) central engine in OJ287 is revealed by impact flares which arise from the secondary impacting the accretion disk of the primary. These flares have been observed since 1913 from the study of old photographic plates and from recent observational campaigns, 9 events in total. In addition, the secondary induces flares by affecting the accretion rate of the primary. The records for the latter events start in 1900, and they have been observed for each of the 10 cycles since then. Because of orbital precession, the impact flares times do not follow any simple rule. However, since the BBH - accretion disk impact model was proposed in 1995, the optical flux behavior of OJ287 has become highly predictable. The latest predictions were given for the late 2015 - early 2017 season. These have now been verified. The impact flare started on 2015 November 25, during the Centenary of Einstein’s General Relativity, followed by induced accretion flares which peaked on 2016 March and 2016 October. The nine impact flares specify the two parameters of the standard accretion disk and the 6 parameters of the BBH orbit uniquely. The main remaining uncertainty has to do with the exact way the gravitational wave (GW) emission affects the orbit. The impact flare observations demand that the GW emission is a combination of the instantaneous and hereditary effects appearing at the Post Newtonian orders 2.5PN, 3.5PN and 4PN, and all of them have to be incorporated while modeling the dynamics of the central engine BBH in OJ287. Previously, only the standard 2.5PN “Newtonian” GW terms have been used. We develop a simplified way of incorporating the higher order General Relativistic effects and obtain revised estimates for various BBH parameters. The improved BBH dynamics makes specific predictions for the occurrences of the expected impact flares in future and thereby provide additional strong field tests of General Relativity.

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