Cosmic Ray Electron Evolution in the Supernova Remnant RX J1713.7-3946

TL;DR

This paper introduces an analytical model for nonthermal electron evolution in supernova remnants and applies it to RX J1713.7-3946, revealing the necessity of multi-zone modeling with compact knots to fit observed spectra.

Contribution

It presents a new analytical formalism for electron acceleration and evolution in SNRs, and demonstrates the importance of multi-zone models to accurately fit observational data.

Findings

Single-zone leptonic models struggle to fit the spectral energy distribution at 1 kpc distance.

Multi-zone models with compact knots and magnetic fields around 16 μG provide better fits.

The model aligns with recent Chandra observations indicating complex structures.

Abstract

A simple formalism to describe nonthermal electron acceleration, evolution, and radiation in supernova remnants (SNRs) is presented. The electron continuity equation is analytically solved assuming that the nonthermal electron injection power is proportional to the rate at which the kinetic energy of matter swept up in an adiabatically expanding SNR shell. We apply this model to \fermi\ and HESS data from the SNR \rxj, and find that a one-zone leptonic model with Compton-scattered cosmic microwave background (CMB) and interstellar infrared photons has difficulty providing a good fit to its spectral energy distribution, provided the source is at a distance $\sim 1\ \kpc$ from the Earth. However, the inclusion of multiple zones, as hinted at by recent {\em Chandra} observations, does provide a good fit, but requires a second zone of compact knots with magnetic fields $B\sim 16\ \mu$G, comparable to shock-compressed fields found in the bulk of the remnant.