Volume 650, June 2021
Parker Solar Probe: Ushering a new frontier in space exploration
|Number of page(s)||6|
|Section||Letters to the Editor|
|Published online||02 June 2021|
Letter to the Editor
Energetic particle behavior in near-Sun magnetic field switchbacks from PSP
Department of Astrophysical Sciences, Princeton University,
2 Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
3 Bartol Research Institute, University of Delaware, Newark, DE 19716, USA
4 University of Arizona, Tucson, AZ 85721, USA
5 University of New Hampshire, Durham, NH 03824, USA
6 Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA
7 Southwest Research Institute, San Antonio, TX 78238, USA
8 University of Texas at San Antonio, San Antonio, TX 78249, USA
9 Physics Department, University of California, Berkeley, CA 94720-7300, USA
10 Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450, USA
11 The Blackett Laboratory, Imperial College London, London, SW7 2AZ, UK
12 School of Physics and Astronomy, Queen Mary University of London, London E1 4NS, UK
13 LPC2E, CNRS and University of Orléans, Orléans, France
14 School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
15 Solar System Exploration Division, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
16 Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA
17 BWX Technologies, Inc., Washington DC 20002, USA
18 Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109, USA
19 Smithsonian Astrophysical Observatory, Cambridge, MA 02138, USA
Accepted: 9 February 2021
Context. The observation of numerous magnetic switchbacks and associated plasma jets in Parker Solar Probe (PSP) during its first five orbits, particularly near the Sun, has attracted considerable attention. Switchbacks have been found to be systematically associated with correlated reversals in the direction of the propagation of Alfvénic fluctuations, as well as similar reversals of the electron strahl.
Aims. Here we aim to see whether the energetic particles change direction at the magnetic field switchbacks.
Methods. We use magnetic field data from the MAG suite’s fluxgate magnetometer instrument to identify switchback regions. We examine the radial anisotropy of the energetic particles measured by the EPI-Lo instrument of the IS⊙IS suite.
Results. We find that energetic particles measured by EPI-Lo generally do not preferentially change their directionality from that of the background magnetic field to that of the switchbacks.
Conclusions. A reasonable hypothesis is that particles with smaller gyroradii, such as strahl electrons, can reverse direction by following the magnetic field in switchbacks, but that larger gyroradii particles cannot. This provides the possibility of setting a constraint on the radius of the curvature of the magnetic field in switchbacks, a property not otherwise observed by PSP. We expect that particles at higher energies than those detectable by EPI-Lo will also not respond to switchbacks. The observed reversals of radial energetic particle flux are separate phenomena, likely associated with source locations or other propagation effects occurring at greater radial distances.
Key words: solar wind / magnetic fields / plasmas / turbulence / instabilities / waves
© ESO 2021
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