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arXiv · 2109.04156

Magnetic Field Structure and Faraday Rotation of the Plerionic Supernova Remnant G21.5$-$0.9

Paul C. W. Lai·C. -Y. Ng·Niccolo' Bucciantini
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Abstract

We present a polarimetric study of the pulsar wind nebula (PWN) in supernova remnant G21.5$-$0.9 using archival Very Large Array (VLA) data. The rotation measure (RM) map of the PWN shows a symmetric pattern that aligns with the presumed pulsar spin axis direction, implying a significant contribution of RM from the nebula. We suggest that the spatial variation of the internal RM is mostly caused by non-uniform distribution of electrons originated from the supernova ejecta. Our high-resolution radio polarization map reveals an overall radial $B$-field. We construct a simple model with an overall radial $B$-field and turbulence in small scale. The model can reproduce many of the observed features of the PWN, including the polarization pattern and polarized fraction. The results also reject a large-scale toroidal $B$-field which implies that the toroidal field observed in the inner PWN cannot propagate to the entire nebula.

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Paul C. W. Lai, C. -Y. Ng, Niccolo' Bucciantini. 2021-09-09. Magnetic Field Structure and Faraday Rotation of the Plerionic Supernova Remnant G21.5$-$0.9. https://doi.org/10.3847/1538-4357%2Fac63b1

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