Short time-scale periodicity in OJ 287

TL;DR

This study analyzes short-term optical variations in blazar OJ 287, confirming a ~50 day periodicity linked to the black hole's ISCO and identifying shorter pseudo-periodic components likely caused by jet re-emission.

Contribution

It provides new observational evidence of short-term periodicities in OJ 287, supporting models of accretion disc spiral waves influencing black hole feeding mechanisms.

Findings

Confirmed ~50 day periodic component in OJ 287

Identified 1-7 day pseudo-periodic components, notably at 3.5 days

Linked the 50 day cycle to a spiral wave in the accretion disc

Abstract

We have studied short-term variations of the blazar OJ 287, suspected to host a supermassive black hole binary. In this study, we use a two-season optical R-band dataset from 2004--2006 which consists of 3991 data points from the OJ 287 observation campaign. It has sections of dense time coverage, and is largely independent from previously published data. We find that this data confirms the existence of a ~50 day periodic component, presumably related to the half-period of the innermost stable circular orbit (ISCO) of the primary black hole. In addition we find several pseudo-periodic components in the 1 to 7 day range, most prominently at 3.5 days, which are likely Lorentz contracted jet re-emission of the 50 day component. The typical 50 day cycle exhibits a slow rise of brightness and a rapid dimming before the start of the new cycle. We explain this as being due to a spiral wave in the accretion disc which feeds the central black hole in this manner.