Hybrid simulations of interstellar pickup protons accelerated at the solar-wind termination shock at multiple locations
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Lunar and Planetary Laboratory, University of ArizonaIssue Date
2021
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IOP Publishing LtdCitation
Giacalone, J., Nakanotani, M., Zank, G. P., Kòta, J., Opher, M., & Richardson, J. D. (2021). Hybrid simulations of interstellar pickup protons accelerated at the solar-wind termination shock at multiple locations. Astrophysical Journal, 911(1).Journal
Astrophysical JournalRights
© 2021. The American Astronomical Society. All rights reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
We estimate the intensity of interstellar pickup protons accelerated to 50 keV at various locations along the solarwind termination shock, using two-dimensional hybrid simulations. Parameters for the solar wind, interstellar pickup ions (PUIs), and magnetic field just upstream of the termination shock at one flank of the heliosphere, and at the location in the downwind (or tail-ward) direction are based on a solar-wind/pickup-ion/turbulence model. The parameters upstream of the shock where Voyager 2 crossed are based on observations. The simulation is limited in size, and therefore cannot accurately model the distribution to energies much beyond 50 keV. This is sufficient to study the origin of the high-energy tail of the distribution, which is the low-energy portion of the anomalous cosmic-ray spectrum. We also extrapolate our results to other locations along the termination shock, such as the other flank, and the poles of the heliosphere. We find that the intensity of 10 50 keV accelerated pickup protons is remarkably similar at all three locations we simulated, suggesting that particles in this energy range are relatively uniformly distributed along the termination shock, and are likely quite uniform throughout the entire heliosheath. In addition, we find significant differences in the distribution in the 0.5 1 keV energy range for energetic neutral atoms coming from the tail region of the heliosphere compared to that at the nose or flank look directions. This is because the peak in the PUI distribution is at a higher energy there. © 2021 Institute of Physics Publishing. All rights reserved.Note
Immediate accessISSN
0004-637XVersion
Final published versionae974a485f413a2113503eed53cd6c53
10.3847/1538-4357/abe93a