Turbulence and Particle Acceleration in Radiative Shock Waves in the Cygnus Loop II: Development of Postshock Turbulence

TL;DR

This study investigates turbulence development behind radiative shock waves in the Cygnus Loop, using high-resolution spectra and imaging to analyze shock morphology and the roles of various instabilities and magnetic fields.

Contribution

It refines shock parameter estimates and applies advanced analysis techniques to understand turbulence development and shock front morphology in supernova remnants.

Findings

Turbulence is influenced by thermal and thin shell instabilities.

Magnetic fields and upstream density variations significantly affect shock structure.

Fourier and Hough Transform techniques effectively quantify shock ripples.

Abstract

Radiative shock waves in the Cygnus Loop and other supernova remnants show different morphologies in [O III] and H{\alpha} emission. We use HST spectra and narrowband images to study the development of turbulence in the cooling region behind a shock on the west limb of the Cygnus Loop. We refine our earlier estimates of shock parameters that were based upon ground-based spectra, including ram pressure, vorticity and magnetic field strength. We apply several techniques, including Fourier power spectra and the Rolling Hough Transform, to quantify the shape of the rippled shock front as viewed in different emission lines. We assess the relative importance of thermal instabilities, the thin shell instability, upstream density variations, and upstream magnetic field variations in producing the observed structure.