J. Chiang and M. Böttcher,
Astrophysical Journal, 564, 92 (2002)
We find that energy losses due to synchrotron self-Compton (SSC) emission
in blazar jets can produce distinctive signatures in the time-averaged
synchrotron and SSC spectra of these objects. For a fairly broad range
of particle injection distributions, SSC-loss dominated synchrotron
emission exhibits a spectral dependence
.
The presence or absence of this dependence in the optical and ultraviolet
spectra of flat spectrum radio quasars such as 3C 279 and in the
soft X-ray spectra of high-frequency BL Lac objects such as Mrk 501
gives a robust measure of the importance of SSC losses. Furthermore,
for partially cooled particle distributions, spectral breaks of varying
sizes can appear in the synchrotron and SSC spectra and will be related
to the spectral indices of the emission below the break. These spectral
signatures place constraints on the size scale and the non-thermal
particle content of the emitting plasma as well as the observer
orientation relative to the jet axis.