Gamma-ray blazars near equipartition and the origin of the GeV spectral break in 3C 454.3

TL;DR

This paper models the GeV spectral break in blazar 3C 454.3 using a log-parabolic electron distribution and near-equipartition conditions, explaining the spectral cutoff via Klein-Nishina effects.

Contribution

It introduces a novel explanation for the GeV spectral break in blazars based on a non-thermal electron population near equipartition, fitting observational data.

Findings

Successfully reproduces the spectral energy distribution of 3C 454.3

Explains the GeV spectral cutoff through Klein-Nishina effects

Supports the equipartition scenario in blazar emission regions

Abstract

Observations performed with the Fermi-LAT telescope have revealed the presence of a spectral break in the GeV spectrum of flat-spectrum radio quasars (FSRQs) and other low- and intermediate-synchrotron peaked blazars. We propose that this feature can be explained by Compton scattering of broad-line region (BLR) photons by a non-thermal population of electrons described by a log-parabolic function. We consider in particular a scenario in which the energy densities of particles, magnetic field, and soft photons in the emitting region are close to equipartition. We show that this model can satisfactorily account for the overall spectral energy distribution of the FSRQ 3C 454.3, reproducing the GeV spectal cutoff due to Klein-Nishina effects and a curving electron distribution.