Particle Acceleration and Synchrotron Self-Compton Emission in Blazar Jets. I. An Application to Quiescent Emission

Abstract

There are still some important unanswered questions about the detailed particle acceleration and escape occurring during the quiescent epoches. As a result, the particle distribution that is adopted in the blazar quiescent spectral model have numerous unconstrained shapes. To help remedy this problem, we introduce a analytical particle transport model to reproduce quiescent broadband spectral energy distribution of blazar. In this model, the exact electron distribution is solved from a generalized transport equation that contains the terms describing first-order and secondary-order Fermi acceleration, escape of particle due to both the advection and spatial diffusion, energy losses due to synchrotron emission and inverse-Compton scattering of an assumed soft photon field. We suggest that the advection is a significant escape mechanism in blazar jet. We find that in our model the advection process tends to harden the particle distribution, which enhances the high energy components of resulting synchrotron and synchrotron self-Comptom spectrum from jet. Our model is able to roughly reproduce the observed spectra of extreme BL Lac object 1ES 0414+009 with reasonable assumptions about the physical parameters.

An Explanation for 13 consecutive days activities of Mrk 421

“…In a phenomenological view, it is interesting and important to find the exclusive characteristic of the emission energy spectrum for tracing the jet microphysics. The present paper introduces a linear acceleration by integrating the reconnection electric field into the particle transport model which has been proposed by Zheng et al (2019). We expected to find the observed evidence for the electrostatic acceleration in the blazar jet.…”

“…The photon spectra in the current context are calculated by the model within the lepton model frame through both synchrotron emission and the IC scattering. In the proposed model, we basically follow the approach of Zheng et al (2019) to calculate the electron spectrum, and we introduce electrostatic acceleration to the first-order gain rate. In our approaches, since the magnetic reconnections occurs in a natural location, we do not take the actual electrostatic acceleration process.…”

“…Using a Green's function to solve the stationary particle transport equation (see e.g., Kroon et al 2016;Zheng et al 2019), we can obtain the closed-form solution for the electron Green's function, N G (γ, γ 0 ),…”

“…where, we let We can use the number density distribution of electrons determined by Eq. ( 4) to calculate the emission intensity of the synchrotron, I syn (ν), and the IC scattering, I ic (ν) in the SSC model frame (e.g., Katarzyński et al 2001;Zheng et al 2019). Taking the absorption effect of the extragalactic background light (EBL) into account, we can calculate the flux density at Earth (e.g., Zheng & Zhang 2011)…”

“…Since we introduce the electrostatic acceleration to the first-order gain rate, we should reestablish the parameter relationships, rather than relying on the model parameters determined in our early work. Based on the equations presented by Zheng et al (2019) and the Eqs. ( 1) and ( 2) in the current context, we find…”