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arXiv · 1311.0936

Time-Dependent Models for Blazar Emissions with the Second-Order Fermi Acceleration

Katsuaki Asano·Fumio Takahara·Masaaki Kusunose·Kenji Toma·Jun Kakuwa
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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 $4.9 \times 10^{38}~\mbox{erg}~\mbox{s}^{-1}$, 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.

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Katsuaki Asano, Fumio Takahara, Masaaki Kusunose, Kenji Toma, Jun Kakuwa. 2013-11-23. Time-Dependent Models for Blazar Emissions with the Second-Order Fermi Acceleration. https://doi.org/10.1088/0004-637x%2F780%2F1%2F64

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