A Model of Polarized X-ray Emission from Twinkling Synchrotron Supernova Shells

TL;DR

This paper models polarized X-ray emission from supernova remnants, showing it is highly clumpy and intermittent due to magnetic field fluctuations, offering a diagnostic for magnetic turbulence and particle acceleration.

Contribution

It introduces a simulation of polarized X-ray emission from SNR shells considering magnetic fluctuations, revealing distinctive polarization patterns and intermittency.

Findings

Polarized X-ray emission is highly clumpy with up to 50% polarization.

Emission exhibits strong intermittency due to magnetic field amplifications.

Characteristics depend on magnetic fluctuation spectra, useful for diagnostics.

Abstract

Synchrotron X-ray emission components were recently detected in many young supernova remnants (SNRs). There is even an emerging class - SN1006, RXJ1713.72-3946, Vela Jr, and others - that is dominated by non-thermal emission in X-rays, also probably of synchrotron origin. Such emission results from electrons/positrons accelerated well above TeV energies in the spectral cut-off regime. In the case of diffusive shock acceleration, which is the most promising acceleration mechanism in SNRs, very strong magnetic fluctuations with amplitudes well above the mean magnetic field must be present. Starting from such a fluctuating field, we have simulated images of polarized X-ray emission of SNR shells and show that these are highly clumpy with high polarizations up to 50%. Another distinct characteristic of this emission is the strong intermittency, resulting from the fluctuating field amplifications. The details of this "twinkling" polarized X-ray emission of SNRs depend strongly on the magnetic-field fluctuation spectra, providing a potentially sensitive diagnostic tool. We demonstrate that the predicted characteristics can be studied with instruments that are currently being considered. These can give unique information on magnetic-field characteristics and high-energy particle acceleration in SNRs.