Non-variable TeV emission from the extended jet of a blazar in the stochastic acceleration scenario: the case of the hard TeV emission of 1ES 1101-232

TL;DR

This paper models the non-variable hard TeV emission from the extended jet of blazar 1ES 1101-232, showing it is dominated by IC/CMB processes and consistent with moderate to high jet beaming.

Contribution

It introduces a stochastic acceleration model for extended jet emission, explaining the TeV emission as IC/CMB and IC/EBL processes, and constrains jet parameters for 1ES 1101-232.

Findings

TeV emission is dominated by IC/CMB from the extended jet.

Physical parameters achieve equipartition at higher Doppler factors.

Moderate to high jet beaming is necessary for the observed emission.

Abstract

The detections of X-ray emission from the kiloparsec-scale jets of blazars and radio galaxies may imply the existence of high energy electrons in these extended jets, and these electrons could produce high energy emission through inverse Compton (IC) process. In this paper we study the non-variable hard TeV emission from a blazar. The multi-band emission consists of two components: one is the traditional synchrotron self-Compton (SSC) emission from the inner jet, and the other is the emission produced via SSC and IC scattering of cosmic microwave background (CMB) photons (IC/CMB) and extragalactic background light (EBL) photons (IC/EBL) by relativistic electrons in the extended jet under the stochastic acceleration scenario. Such a model is applied to 1ES 1101-232. The results indicate that (1) the non-variable hard TeV emission of 1ES 1101-232 can be reproduced well, which is dominated by IC/CMB emission from the extended jet, using three characteristic values of Doppler factor ($\delta_{\rm D}=5,10,15$) for the TeV emitting region in the extended jet; and (2) in the cases of $\delta_{\rm D}=15$ and 10, the physical parameters can achieve the equipartition (or quasi-equipartition) between the relativistic electrons and the magnetic field; In contrast, the physical parameters largely deviate from the equipartition for the case of $\delta_{\rm D}=5$. It is therefore concluded that the TeV emission region of 1ES 1101-232 in the extended jet should be moderately or highly beamed.