From astrobites: “Exploding stars and sleight of hand: A case of magnetic misdirection”

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Title: When Disorder Looks Like Order: A New Model to Explain Radial Magnetic Fields in Young Supernova Remnants
Authors: J. L. West, T. Jaffe, G. Ferrand, S. Safi-Harb, and B. M. Gaensler
First Author’s Institution: Dunlap Institute for Astronomy and Astrophysics at the University of Toronto, Canada

Status: Published in The Astrophysical Journal Letters, open access on arXiv

In the roiling outer layers of exploding stars, electrons are accelerated to near light speed. These relativistic electrons have a habit of causing glitches in orbiting spacecraft and sparking showers of secondary particles. Striking the retinae of in-orbit astronauts, they generate flashes of phantom light.

How do these electrons reach their enormously high velocities? The exact mechanism isn’t known, but it’s thought to depend upon the magnetic fields threaded throughout the expanding shells of young supernova remnants. Curiously, as shown in Figure 1, many young supernova remnants appear to have well-ordered radial magnetic fields, pointing neatly away from or toward the center of the explosion. While it’s not impossible for the magnetic field to be orderly, it’s reasonable to expect that the explosion of a dying star, which creates swirling knots and curlicues of hot plasma, would impart some turbulence and randomness to its magnetic field. Could the neat, radial pattern that we observe belie the true, messy magnetic field? If so, how can we tell?

Figure 3. Simulated polarized intensity (color scale) and simulated magnetic field orientations (black lines) for a turbulent intrinsic field and three different acceleration mechanisms. Although the isotropic electron acceleration mechanism (left) yields an apparently random magnetic field, the quasi-parallel (center) and quasi-perpendicular (right) acceleration mechanisms generate apparently ordered magnetic fields. Adapted from Figure 4 in the paper.

See the full article here .

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