Fast variability of gamma-ray emission from supermassive black hole binary OJ 287

TL;DR

This study reports rapid gamma-ray variability from blazar OJ 287, indicating jet emission from the less massive black hole in a supermassive binary system, providing insights into jet formation mechanisms.

Contribution

It presents the first detection of sub-10 hour gamma-ray variability from OJ 287, linking emission to the smaller black hole and constraining jet parameters.

Findings

Gamma-ray variability time scale < 3-10 hours.

Doppler factor of jet > 4.

Detection of >10 GeV gamma rays during flares.

Abstract

We report the discovery of fast variability of gamma-ray flares from blazar OJ 287. This blazar is known to be powered by binary system of supermassive black holes. The observed variability time scale T_var < 3-10 hr is much shorter than the light crossing time of more massive (1.8x10^10 solar masses) black hole and is comparable to the light crossing time of the less massive (1.3x10^8 solar masses) black hole. This indicates that gamma-ray emission is produced by relativistic jet ejected by the black hole of smaller mass. Detection of gamma rays s with energies in excess of 10 GeV during the fast variable flares constrains the Doppler factor of the jet to be larger than 4. Possibility of the study of orbital modulation of emission from relativistic jet makes OJ 287 a unique laboratory for the study of the mechanism(s) of formation of jets by black holes, in particular, of the response of the jet parameters to the changes of the parameters of the medium from which the black hole accretes and into which the jet expands.