When disorder looks like order: a new model to explain radial magnetic fields in young supernova remnants

Abstract

Radial magnetic fields are observed in all known young, shell-type supernova remnants (SNRs) in our Galaxy, including Cas A, Tycho, Kepler, and SN1006 and yet the nature of these radial fields has not been thoroughly explored. Using a 3D model, we consider the existence and observational implications of an intrinsically radial field. We also present a new explanation of the origin of the radial pattern observed from polarization data as resulting from a selection effect due to the distribution of cosmic-ray electrons (CREs). We show that quasi-parallel acceleration can concentrate CREs at regions where the magnetic field is radial, making a completely turbulent field appear ordered, when it is in fact disordered. We discuss observational properties that may help distinguish between an intrinsically radial magnetic field and the case where it only appears radial due to the CRE distribution. We also show that the case of an intrinsically radial field with a quasi-perpendicular CRE acceleration mechanism has intriguing similarities to the observed polarization properties of SN1006.

7 pages, 5 figures, Published 2017 November 3, The Astrophysical Journal Letters, Volume 849, Number 2

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• Probing Magnetic Fields in Young Supernova Remnants with IXPE
• Polarized Emission From Four Supernova Remnants In The THOR Survey
• Polarized radio emission unveils the structure of the pre-supernova circumstellar magnetic field and the radio emission in SN1987A
• On the Potential of Faraday Tomography to Identify Shock Structures in Supernova Remnants
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• A new wideband radio polarization observation of the Supernova Remnant G315.4$-$2.3
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