Modeling the Spectral Energy Distributions and Variability of Blazars
  In this review, recent progress in theoretical models for the broadband
(radio through gamma-ray) emission from blazars are summarized. The salient
features of both leptonic and hadronic models are reviewed. I present sample
modeling results of spectral energy distributions (SEDs) of different types of
Fermi-detected blazars along the traditional blazar sequence, using both types
of models. In many cases, the SEDs of high-frequency peaked blazars (HBLs) have
been found to be well represented by simple synchrotron + synchrotron
self-Compton (SSC) models. However, a few HBLs recently discovered as
very-high-energy (VHE) gamma-ray emitters by VERITAS are actually better
represented by either external-Compton or hadronic models. Often, spectral
modeling with time-independent single-zone models alone is not sufficient to
constrain models, as both leptonic and lepto-hadronic models are able to
provide acceptable fits to the overall SED. This degeneracy can be lifted by
considering further constraints from spectral variability. Recent developments
of time-dependent and inhomogeneous blazar models will be discussed, including
detailed numerical simulations as well as a semi-analytical approach to the
time-dependent radiation signatures of shock-in-jet models.
