Revisiting the proton synchrotron radiation in blazar jets: Possible contributions from X-ray to $\gamma$-ray bands

Abstract

The proton synchrotron radiation is considered as the origin of high-energy emission of blazars at times. However, extreme physical parameters are often required. In this work, we propose an analytical method to study the parameter space when applying the proton synchrotron radiation to fit the keV, GeV, and very-high-energy emission of blazar jets. We find that proton synchrotron radiation can fit the high-energy hump when it peaks beyond tens GeV without violating basic observations and theories. For the high-energy hump peaked around GeV band, extreme parameters, such as a super-Eddington jet power and a very strong magnetic field, are required. For the high-energy hump peaked around keV band, if an acceptable parameter space can be found depends on the object's keV luminosity.