Spine-sheath jet model for low-luminosity AGNs

TL;DR

This paper introduces a detailed numerical model for structured spine-sheath jets in low-luminosity AGNs, incorporating particle interactions, feedback between zones, and shear acceleration to better understand jet emission mechanisms.

Contribution

The paper presents a novel, comprehensive numerical framework for modeling particle and radiation transport in two-zone spine-sheath AGN jets, including shear acceleration effects.

Findings

First application to low-luminosity AGNs shows significant shear acceleration effects.

Model captures complex particle interactions and feedback between jet zones.

Provides a versatile tool for simulating structured jet emission processes.

Abstract

In several jetted AGNs, structured jets have been observed. In particular spine-sheath configurations where the jet is radially divided into two or more zones of different flow velocities. We present a model based on the particle and radiation transport code CR-ENTREES. Here, interaction rates and secondary particle and photon yields are pre-calculated by Monte Carlo event generators or semi-analytical approximations. These are then used to create transition matrices, that describe how each particle spectrum evolves with time. This code allows for arbitrary injection of primary particles, and the possibility to choose which interaction to include (photo-meson production, Bethe-Heitler pair-production, inverse-Compton scattering, $\gamma$-$\gamma$ pair production, decay of all unstable particles, synchrotron radiation -- from electrons, protons, and all relevant secondaries before their respective decays -- and particle escape). In addition to the particle and radiation interactions taking place in each homogeneous zone, we implement the feedback between the two zones having different bulk velocities. The main mechanism at play when particles cross the boundary between the two zones is shear acceleration. We follow a microscopic description of this acceleration process to create a corresponding transition matrix and include it in our numerical setup. Furthermore, each zone's radiation field can be used as an external target photon field for the other zone's particle interactions. We present here the first results of the effect of a two-zone spine-sheath jet, by applying this model to typical low-luminosity AGNs.