Relativistic jet meets target - The gamma-rays from 3C 273

Gamma-rays dominate the emission from quasar 3C 273, although they cannot arise in its active center. Their origin is ascribed to a relativistic beam which entrains and clumps ambient cluster gas. Secondary electrons from nuclear collisions lead to bremsstrahlung gamma-rays and ultimately to a double radio source. This model requires a great deal of clumping of jet and target matter to get sufficient reactions to occur. The clumping required is consistent with the Liouville theorem, given the high collimation of the beam, which suggests that the process, however unexpected, is at least thermodynamically permitted. The present model is experimentally distinguishable from other models through its location of the X-ray source in the extended optical jet region, and through a number of detailed spectral features.