Time-Dependent Models for Blazar Emissions with the Second-Order Fermi Acceleration
Abstract
The second-order Fermi acceleration (Fermi-II) driven by turbulence may be responsible for the electron acceleration in blazar jets. We test this model with time-dependent simulations. The hard electron spectrum predicted by the Fermi-II process agrees with the hard photon spectrum of 1ES 1101-232. For other blazars that show softer spectra, the Fermi-II model requires radial evolution of the electron injection rate and/or diffusion coefficient in the outflow. Such evolutions can yield a curved electron spectrum, which can reproduce the synchrotron spectrum of Mrk 421 from the radio to the X-ray regime.The photon spectrum in the GeV energy range of Mrk 421 is hard to fit with a synchrotron self-Compton model. However, if we introduce an external radio photon field with a luminosity of , GeV photons are successfully produced via inverse Compton scattering. The temporal variability of the diffusion coefficient or injection rate causes flare emission. The observed synchronicity of X-ray and TeV flares implies a decrease of the magnetic field in the flaring source region.
Cite
@article{arxiv.1311.0936,
title = {Time-Dependent Models for Blazar Emissions with the Second-Order Fermi Acceleration},
author = {Katsuaki Asano and Fumio Takahara and Masaaki Kusunose and Kenji Toma and Jun Kakuwa},
journal= {arXiv preprint arXiv:1311.0936},
year = {2015}
}
Comments
34 pages, 15 figures, accepted for publication in the Astrophysical Journal