High Energy Emission Processes and Parsec Scale Environment of OJ 287

The detection of gamma-ray flare from the BL Lac object, OJ 287 during October 2009 is associated with the ejection of a superluminal knot and increased linear polarization as suggested by the 7 mm very long baseline array observations. We study plausible mechanisms responsible for the high energy emission (X-rays to gamma-rays) using the contemporaneous multi-wavelength observations from radio to gamma -rays during this period. Using a simple one zone leptonic model, incorporating synchrotron and inverse Compton emission processes, we show that the high energy emission cannot be explained by either synchrotron-self Compton (SSC) or external Compton (EC) processes alone. However, a combination of both
SSC and EC can successfully reproduce the observed high energy spectrum. The temperature of external photon field inferred from this model suggests that the gamma-ray emission region is surrounded by a warm infra-red (IR) emitting region of ~ 240 K. Assuming this IR emitting region as a spherical cloud illuminated by ultra-violet (UV) emission from accretion disk, we estimated the location of emission region to be ~ 10 pc, supporting the claim that the gamma-ray emission from OJ 287 during 2009 flare arises from a location far away from the central engine.