A polarization study of the supernova remnant CTB 80

TL;DR

This study analyzes the polarization properties of supernova remnant CTB 80 across multiple radio frequencies, revealing complex magnetic field structures and a potential new shell feature, advancing understanding of supernova remnant magnetic environments.

Contribution

It provides the first detailed polarization and rotation measure map of CTB 80, identifying a possible new shell structure and magnetic field variations.

Findings

Rotation measure changes sign along the shell

Identification of a bright polarized shell structure

Uncertainty about the nature of the partial shell

Abstract

We present a radio polarization study of the supernova remnant CTB 80 based on images at 1420 MHz from the Canadian Galactic plane survey, at 2695 MHz from the Effelsberg survey of the Galactic plane, and at 4800 MHz from the Sino-German 6cm polarization survey of the Galactic plane. We obtained a rotation measure (RM) map using polarization angles at 2695 MHz and 4800 MHz as the polarization percentages are similar at these two frequencies. RM exhibits a transition from positive values to negative values along one of the shells hosting the pulsar PSR B1951+32 and its pulsar wind nebula. The reason for the change of sign remains unclear. We identified a partial shell structure, which is bright in polarized intensity but weak in total intensity. This structure could be part of CTB 80 or part of a new supernova remnant unrelated to CTB 80.