Revealing the Nature and Location of High Energy Emission in the Candidate Binary SMBH System OJ 287

Understand

The latest flare of the regular $\sim$ 12 years quasi-periodic optical outbursts in the binary SMBH candidate system OJ 287 occurred in December 2015.

• Following this, the source has exhibited enhanced multi-wavelength (MW) variability in spectral, temporal and polarization domains with new features never seen before.
• Our MW investigation show that the overall MW variability can be divided into two-phase, (i) November 2015 -- May 2016 with variability from near-infrared (NIR) to Fermi-LAT $\rm \gamma$-ray energies (0.1 -- 300 GeV), and (ii) September 2016 -- July 2017 with intense NIR to X-ray variability but without any activity in the Fermi-LAT band, and the very first detection at very high energies (VHEs, E $>$ 100 GeV) by VERITAS.
• The broadband SEDs during the first phase show a thermal bump in the NIR-optical region and a hardening in the $\rm \gamma$-ray spectra with a shift in its peak.