Magnetic Structures and Turbulence in SN 1006 Revealed with Imaging X-Ray Polarimetry

Abstract

Young supernova remnants strongly modify the surrounding magnetic fields, which in turn play an essential role in accelerating cosmic rays (CRs). The 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 SN 1006 from a 1 Ms observation with the Imaging X-ray Polarimetry Explorer. We found an average polarization degree of 22.4% ± 3.5% and an average polarization angle of −45.°4 ± 4.°5 (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 magnetic turbulence in SN 1006, and CR acceleration is environment-dependent.

X-Ray Polarization of the Eastern Lobe of SS 433

“…Young, shell-type supernova remnants show radio EVPAs perpendicular to the flow near the shocks in the outer rims. Recent IXPE observations show similar EVPAs, typically with higher PDs, in the X-ray band (Vink et al 2022;Ferrazzoli et al 2023;Zhou et al 2023). These results indicate magnetic fields parallel to the flow, as seen here.…”

“…These backgrounds appear as short-term increases in counting rate, and we removed times when the count rate was higher than the mean rate plus 3 times the rms of the rate (Forsblom et al 2023). The technique has been important for the study of faint sources such as Galactic center clouds and supernova remnants with IXPE (Marin et al 2023;Zhou et al 2023). After filtering, the total livetime was 800.7, 791.8, and 789.2 ks for DU1, DU2, and DU3, respectively.…”

Discovery of a Shock-compressed Magnetic Field in the Northwestern Rim of the Young Supernova Remnant RX J1713.7–3946 with X-Ray Polarimetry

“…This demonstrates that the processes responsible for radial magnetic fields observed in young SNRs are already at work at the scales where X-rays are emitted. The lowest PD of the nonthermal emission was reported for Cas A (Vink et al 2022), PD ∼ 5%, followed by Tycho (Ferrazzoli et al 2023), PD ∼ 12%, and finally by SN 1006 (Zhou et al 2023), PD ∼ 22%. Comparing the X-ray polarization measurements of these three remnants, the remarkable similarity in the radially oriented magnetic field is in contrast with the very different PD, likely reflecting a decreasing level of magnetic field turbulence.…”

“…IXPE previously detected significant polarization in three younger SNRs: Cas A (Vink et al 2022), Tycho (Ferrazzoli et al 2023), and SN 1006 (Zhou et al 2023), all showing radially oriented magnetic fields. This demonstrates that the processes responsible for radial magnetic fields observed in young SNRs are already at work at the scales where X-rays are emitted.…”

MeerKAT 1.3 GHz Observations of Supernova Remnants

“…6.2.3. G327.6 + 14.6 (SN1006) X-ray imaging polarimetry of the northeast region of this SNR is reported in Zhou et al (2023). The X-ray polarization shows that the magnetic field is predominantly radial with an average fractional polarization of 22 ± 4%.…”