Models for the Spectral Energy Distributions and Variability of Blazars

Markus Boettcher

Published 2010-06-25Version 1

In this review, recent progress in theoretical models for blazar emission will be summarized. The salient features of both leptonic and lepto-hadronic approaches to modeling blazar spectral energy distributions will be reviewed. I will present sample modeling results of spectral energy distributions (SEDs) of different types of blazars along the blazar sequence, including Fermi high-energy gamma-ray data, using both types of models. Special emphasis will be placed on the implications of the recent very-high-energy (VHE) gamma-ray detections of non-traditional VHE gamma-ray blazars, including intermediate and low-frequency-peaked BL Lac objects and even flat-spectrum radio quasars. Due to the featureless optical spectra of BL Lac objects, the redshifts of several BL Lacs remain unknown. I will briefly discuss possible constraints on their redshift using spectral modeling of their SED including Fermi + ground-based VHE gamma-ray data. It will be shown that in some cases, 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. Subsequently, 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.