Abstract
Reinhard Schlickeiser has made groundbreaking contributions to various aspects of blazar physics, including diffusive shock acceleration, the theory of synchrotron radiation, the production of gamma-rays through Compton scattering in various astrophysical sources, etc. This paper, describing the development of a self-consistent shock-in-jet model for blazars with a synchrotron mirror feature, is therefore an appropriate contribution to a Special Issue in honor of Reinhard Schlickeiser’s 70th birthday. The model is based on our previous development of a self-consistent shock-in-jet model with relativistic thermal and non-thermal particle distributions evaluated via Monte-Carlo simulations of diffusive shock acceleration, and time-dependent radiative transport. This model has been very successful in modeling spectral variability patterns of several blazars, but has difficulties describing orphan flares, i.e., high-energy flares without a significant counterpart in the low-frequency (synchrotron) radiation component. As a solution, this paper investigates the possibility of a synchrotron mirror component within the shock-in-jet model. It is demonstrated that orphan flares result naturally in this scenario. The model’s applicability to a recently observed orphan gamma-ray flare in the blazar 3C279 is discussed and it is found that only orphan flares with mild (≲ a factor of 2–3) enhancements of the Compton dominance can be reproduced in a synchrotron-mirror scenario, if no additional parameter changes are invoked.
Highlights
Synchrotron Mirror Model for Blazars are a class of jet-dominated active galactic nuclei
This is the basis of a class of models termed synchrotron mirror models, where the synchrotron radiation of the high-energy emission region traveling along the jet, is reflected by a cloud to re-enter the emission region at a later time
As detailed in the introduction, the study of the synchrotron mirror model developed here was motivated by the difficulties in modeling the orphan γ-ray flare B of 3C279 in December 2013 reported by Hayashida et al [36]
Summary
Synchrotron Mirror Model for Blazars are a class of jet-dominated active galactic nuclei. In two recent papers [30,31], we had coupled Monte-Carlo simulations of diffusive shock acceleration (DSA), using the code of Summerlin and Baring [29], with timedependent radiation transfer, based on radiation modules originally developed by Böttcher, Mause and Schlickeiser in 1997 [32] and further developed as detailed in [33,34] In those studies, we found that the particles’ mean free path for pitch-angle scattering, λpas , which mediates the first-order Fermi process in DSA, must have a strong dependence on particle momentum, with an index α > 1 for a parameterization of λpas ( p) ∝ pα. One plausible way of producing orphan γ-ray flares in the framework of a leptonic single-zone blazar model is the temporary enhancement of an external radiation field that serves as target for inverse-Compton scattering This is the basis of a class of models termed synchrotron mirror models, where the synchrotron radiation of the high-energy emission region traveling along the jet, is reflected by a cloud to re-enter the emission region at a later time.
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