Magnetic structures and turbulence in SN 1006 revealed with imaging X-ray polarimetry

TL;DR

This study uses X-ray polarimetry to analyze magnetic field structures and turbulence in SN 1006, revealing nearly radial magnetic fields and environment-dependent cosmic ray acceleration mechanisms.

Contribution

First X-ray polarization measurements of SN 1006's northeastern shell, providing insights into magnetic field morphology and turbulence related to cosmic ray acceleration.

Findings

Magnetic fields are nearly parallel to the shock normal.

X-ray polarization degree is higher than in radio observations.

CR-induced instabilities likely drive turbulence in SN 1006.

Abstract

Young supernova remnants (SNRs) strongly modify surrounding magnetic fields, which in turn play an essential role in accelerating cosmic rays (CRs). X-ray polarization measurements probe magnetic field morphology and turbulence at the immediate acceleration site. We report the X-ray polarization distribution in the northeastern shell of SN1006 from a 1 Ms observation with the Imaging X-ray Polarimetry Explorer (IXPE). We found an average polarization degree of $22.4\pm 3.5\%$ and an average polarization angle of $-45.4\pm 4.5^\circ$ (measured on the plane of the sky from north to east). The X-ray polarization angle distribution reveals that the magnetic fields immediately behind the shock in the northeastern shell of SN 1006 are nearly parallel to the shock normal or radially distributed, similar to that in the radio observations, and consistent with the quasi-parallel CR acceleration scenario. The X-ray emission is marginally more polarized than that in the radio band. The X-ray polarization degree of SN 1006 is much larger than that in Cas A and Tycho, together with the relatively tenuous and smooth ambient medium of the remnant, favoring that CR-induced instabilities set the turbulence in SN 1006 and CR acceleration is environment-dependent.