Temperature, brightness and spectral index of the Cygnus radio loop

TL;DR

This paper measures the brightness and spectral index of the Cygnus supernova remnant across multiple radio frequencies, confirming its non-thermal origin and suggesting it evolved in a low-density environment.

Contribution

It provides new multi-frequency brightness measurements and spectral analysis of the Cygnus loop using a previously developed method, demonstrating its applicability to supernova remnants.

Findings

Confirmed non-thermal origin of Cygnus loop

Estimated spectral index across frequencies

Indicated evolution in low-density environment

Abstract

The estimated brightness of the Cygnus loop supernova remnant (SNR) at 2720, 1420, 820, 408 and 34.5 MHz are presented. The observations of the continuum radio emission are used to calculate the mean brightness temperatures and surface brightnesses of this loop at the five frequencies in wide spectral range, using the method we have previously developed for large radio loops. The spectrum for mean temperatures versus frequency between the five frequencies is estimated and the spectral index of Cygnus loop is also obtained. Also, from our results can be concluded that Cygnus loop evolves in the low density environment and the initial energy of supernova explosion was relatively low. The obtained results confirm non-thermal origin of the Cygnus radio loop and show that our method is applicable to almost all remnants.