A STATISTICAL-METHOD OF TESTING THE GAMMA-RAY EMISSION MECHANISMS OF BLAZARS

Models for generation of high energy gamma rays in blazars can be clas sified into two types of mechanisms in the jet comoving frame: relativ istic electron scattering on the internal photons or magnetic field (v irtual photons) (SIP) and on the external photons (SEP). These two mec hanisms are known to result in a significant difference in the beaming effect. In this work, we propose a statistical test for the two types of mechanisms based on the beaming difference. The random variable is taken to be the K-corrected gamma ray to radio flux ratio and its dis tribution is shown to be a power-law with an index being model-depende nt. The feasibility of such a test is investigated with a limited samp le of data which are complied from the EGRET gamma ray survey, low res olution radio surveys and a VLBI radio survey. A correlation study ind icates that the VLBI data are more suitable for the purpose than the l ow resolution data. Due to the limited amount of available data, the c urrent test result is not statistically significant to discriminate th e two emission mechanisms. Future generation of high energy gamma ray telescopes are needed to produce a larger sample of data of gamma ray blazars and their simultaneous observations with VLBI are called.