Synchrotron and Synchrotron Self‐Compton Spectral Signatures and Blazar Emission Models

We find that energy losses due to synchrotron self-Compton (SSC) emission inblazar jets can produce distinctive signatures in the time-averaged synchrotronand SSC spectra of these objects. For a fairly broad range of particleinjection distributions, SSC-loss dominated synchrotron emission exhibits aspectral dependence $F_\nu \sim \nu^{-3/2}$. The presence or absence of thisdependence in the optical and ultraviolet spectra of flat spectrum radioquasars such as 3C~279 and in the soft X-ray spectra of high frequency BL Lacobjects such as Mrk 501 gives a robust measure of the importance of SSC losses.Furthermore, for partially cooled particle distributions, spectral breaks ofvarying sizes can appear in the synchrotron and SSC spectra and will be relatedto the spectral indices of the emission below the break. These spectralsignatures place constraints on the size scale and the non-thermal particlecontent of the emitting plasma as well as the observer orientation relative tothe jet axis.Comment: 4 pages, 1 figure, LaTeX2e, emulateapj5.sty, accepted for publication in Ap