Combined synchrotron and nonlinear synchrotron-self-Compton cooling of relativistic electrons

Abstract

The broadband SEDs of blazars exhibit two broad spectral components,which in leptonic emission models are attributed to synchrotron radiationand SSC radiation of relativistic electrons. During high state phases,the high-frequency SSC component often dominates the low-frequencysynchrotron component, implying that the inverse Compton SSC lossesof electrons are at least equal to or greater than the synchrotronlosses of electrons. The linear synchrotron cooling, usually includedin radiation models of blazars, then has to be supplemented by theSSC cooling. Here, we present an analytical solution to the kineticequation of relativistic electrons subject to the combined synchrotronand nonlinear synchrotron self-Compton cooling for monoenergeticinjection. We calculate the time-dependent fluxes and time-integratedfluences resulting from monoenergetic electrons cooling via synchrotronand SSC, and suggest this as a model for the broadband SED of Compton-dominatedblazars.