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27th of June 2018
Linear polarization in SN1987A
(by Zanardo et al.)
Zanardo et al. have used the Australia Telescope Compact Array to make the first detection of linear polarization of in the radio emission from the remnant of supernova 1987A in the Large Magellanic Cloud. The direction of the radio polarization, corrected for Faraday rotation, points to a primarily radial magnetic field across the inner ring. The magnetic field strength peaks over the high-emissivity eastern sites, where efficient cosmic ray acceleration likely takes place. The mean fraction of polarized emission in the brightest sites is 2.7 +/- 0.2% at 22 GHz and 3.5 +/- 0.7% at 44 GHz. SN 1987A is proving to be a unique laboratory to investigate particle acceleration in young supernova remnants.

The image above shows the polarized intensity in SN 1987A as the colour scale, which is overlaid with the contours (blue) of the contemporaneous Stokes-I image of the SNR at 44 GHz. The polarization vectors have been rotated by 90 degrees to show the intrinsic magnetic field orientation (orange-coloured lines). Each vector's length is proportional to the fractional polarization; the line extent corresponding to P = 100% is shown at the bottom. The paper describing the results has been accepted for publication in the Astrophysical Journal Letters.

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