Probing the Jet Power of the Blazar OJ 287 from Broadband SED Modelling

Abstract

OJ 287 is one of the best-studied BL Lac objects, exhibiting strong multiwave-length variability and serving as an excellent laboratory for investigating relativistic jet physics. We present a broadband spectral energy distribution (SED) study of its December 2015 flare using quasi-simultaneous optical/UV, X-ray, and γ-ray obser-vations. The SED is modelled within a one-zone leptonic framework using Broken Power-Law (BPL) and Log-Parabola (LP) electron energy distributions. The best-fitting models constrain key jet parameters, including the magnetic field strength, emission region size, bulk Lorentz factor, and particle energy distribution. We estimate the jet power and its contributions from relativistic particles, magnetic fields, and radiation. The results indicate a particle-dominated jet with efficient high-energy emission and significant Doppler boosting during the flare, providing important insights into the jet energetics and emission mechanisms of OJ 287.