Probing solar flare accelerated electron distributions with prospective X-ray polarimetry missions

Jeffrey, N. L.S., Saint-Hilaire, P. and Kontar, E. P. (2020) Probing solar flare accelerated electron distributions with prospective X-ray polarimetry missions. Astronomy and Astrophysics, 642, A79. (doi: 10.1051/0004-6361/202038626)

Abstract

Solar flare electron acceleration is an extremely efficient process, but the method of acceleration is not well constrained. Two of the essential diagnostics, electron anisotropy (velocity angle to the guiding magnetic field) and the high energy cutoff (highest energy electrons produced by the acceleration conditions: mechanism, spatial extent, and time), are important quantities that can help to constrain electron acceleration at the Sun but both are poorly determined. Here, by using electron and X-ray transport simulations that account for both collisional and non-collisional transport processes, such as turbulent scattering and X-ray albedo, we show that X-ray polarization can be used to constrain the anisotropy of the accelerated electron distribution and the most energetic accelerated electrons together. Moreover, we show that prospective missions, for example CubeSat missions without imaging information, can be used alongside such simulations to determine these parameters. We conclude that a fuller understanding of flare acceleration processes will come from missions capable of both X-ray flux and polarization spectral measurements together. Although imaging polarimetry is highly desired, we demonstrate that spectro-polarimeters without imaging can also provide strong constraints on electron anisotropy and the high energy cutoff.

• Item Type: Articles
• Additional Information: The development of the electron and photon transport models are part of an international team grant (“Solar flare acceleration signatures and their connection to solar energetic particles” http://www.issibern.ch/teams/solflareconnectsolenerg/) from ISSI Bern, Switzerland. NLSJ acknowledges IDL support provided by the UK Science and Technology Facilities Council (STFC).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Kontar, Professor Eduard
• Authors: Jeffrey, N. L.S., Saint-Hilaire, P., and Kontar, E. P.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Astronomy and Astrophysics
• Publisher: EDP Sciences
• ISSN: 0004-6361
• ISSN (Online): 1432-0746
• Published Online: 07 October 2020
• Copyright Holders: Copyright © 2020 ESO
• First Published: First published in 642:A79
• Publisher Policy: Reproduced in accordance with the publisher copyright policy

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