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Title: Ultrarelativistic electron butterfly distributions created by parallel acceleration due to magnetosonic waves

The Van Allen Probe observations during the recovery phase of a large storm that occurred on 17 March 2015 showed that the ultrarelativistic electrons at the inner boundary of the outer radiation belt (L* = 2.6–3.7) exhibited butterfly pitch angle distributions, while the inner belt and the slot region also showed evidence of sub-MeV electron butterfly distributions. In this paper, strong magnetosonic waves were observed in the same regions and at the same time periods as these butterfly distributions. Moreover, when these magnetosonic waves extended to higher altitudes (L* = 4.1), the butterfly distributions also extended to the same region. Combining test particle calculations and Fokker-Planck diffusion simulations, we successfully reproduced the formation of the ultrarelativistic electron butterfly distributions, which primarily result from parallel acceleration caused by Landau resonance with magnetosonic waves. Finally, the coexistence of ultrarelativistic electron butterfly distributions with magnetosonic waves was also observed in the 24 June 2015 storm, providing further support that the magnetosonic waves play a key role in forming butterfly distributions.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ; ORCiD logo [1] ;  [2] ; ORCiD logo [3] ;  [4] ;  [5] ;  [6] ;  [6] ;  [6] ;  [7] ;  [4]
  1. Univ. of California, Los Angeles, CA (United States). Dept. of Atmospheric and Oceanic Sciences
  2. Univ. of Colorado, Boulder, CO (United States). Lab. for Atmospheric and Space Physics
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. The Aerospace Corporation, El Segundo, CA (United States). Space Science Applications Lab.
  5. Univ. of New Hampshire, Durham, NH (United States). Inst. for the Study of Earth, Oceans, and Space
  6. Univ. of Iowa, Iowa City, IA (United States). Dept. of Physics and Astronomy
  7. Univ. of California, Los Angeles, CA (United States). Dept. of Earth, Planetary, and Space Sciences. Inst. of Geophysics and Planetary Physics
Publication Date:
Report Number(s):
LA-UR-16-23142
Journal ID: ISSN 2169-9380
Grant/Contract Number:
AC52-06NA25396; NAS5-01072; NNX13AI61G; NNX11AR64G; NNX15AF61G; NNX15AI96G; 921647; 967399; AGS-1103064; 1001057397:01; 13-041; FA9550-15-1-0158
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Volume: 121; Journal Issue: 4; Journal ID: ISSN 2169-9380
Publisher:
American Geophysical Union
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of California, Los Angeles, CA (United States); The Aerospace Corporation, El Segundo, CA (United States); Univ. of Iowa, Iowa City, IA (United States)
Sponsoring Org:
USDOE; National Aeronautic and Space Administration (NASA); National Science Foundation (NSF); US Air Force Office of Scientific Research (AFOSR)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; butterfly distributions; magnetosonic waves; radiation belt; Landau resonance; ultrarelativistic electrons
OSTI Identifier:
1467365

Li, Jinxing, Bortnik, Jacob, Thorne, Richard M., Li, Wen, Ma, Qianli, Baker, Daniel N., Reeves, Geoffrey D., Fennell, Joseph F., Spence, Harlan E., Kletzing, Craig A., Kurth, William S., Hospodarsky, George B., Angelopoulos, Vassilis, and Blake, J. Bernard.. Ultrarelativistic electron butterfly distributions created by parallel acceleration due to magnetosonic waves. United States: N. p., Web. doi:10.1002/2016JA022370.
Li, Jinxing, Bortnik, Jacob, Thorne, Richard M., Li, Wen, Ma, Qianli, Baker, Daniel N., Reeves, Geoffrey D., Fennell, Joseph F., Spence, Harlan E., Kletzing, Craig A., Kurth, William S., Hospodarsky, George B., Angelopoulos, Vassilis, & Blake, J. Bernard.. Ultrarelativistic electron butterfly distributions created by parallel acceleration due to magnetosonic waves. United States. doi:10.1002/2016JA022370.
Li, Jinxing, Bortnik, Jacob, Thorne, Richard M., Li, Wen, Ma, Qianli, Baker, Daniel N., Reeves, Geoffrey D., Fennell, Joseph F., Spence, Harlan E., Kletzing, Craig A., Kurth, William S., Hospodarsky, George B., Angelopoulos, Vassilis, and Blake, J. Bernard.. 2016. "Ultrarelativistic electron butterfly distributions created by parallel acceleration due to magnetosonic waves". United States. doi:10.1002/2016JA022370. https://www.osti.gov/servlets/purl/1467365.
@article{osti_1467365,
title = {Ultrarelativistic electron butterfly distributions created by parallel acceleration due to magnetosonic waves},
author = {Li, Jinxing and Bortnik, Jacob and Thorne, Richard M. and Li, Wen and Ma, Qianli and Baker, Daniel N. and Reeves, Geoffrey D. and Fennell, Joseph F. and Spence, Harlan E. and Kletzing, Craig A. and Kurth, William S. and Hospodarsky, George B. and Angelopoulos, Vassilis and Blake, J. Bernard.},
abstractNote = {The Van Allen Probe observations during the recovery phase of a large storm that occurred on 17 March 2015 showed that the ultrarelativistic electrons at the inner boundary of the outer radiation belt (L* = 2.6–3.7) exhibited butterfly pitch angle distributions, while the inner belt and the slot region also showed evidence of sub-MeV electron butterfly distributions. In this paper, strong magnetosonic waves were observed in the same regions and at the same time periods as these butterfly distributions. Moreover, when these magnetosonic waves extended to higher altitudes (L* = 4.1), the butterfly distributions also extended to the same region. Combining test particle calculations and Fokker-Planck diffusion simulations, we successfully reproduced the formation of the ultrarelativistic electron butterfly distributions, which primarily result from parallel acceleration caused by Landau resonance with magnetosonic waves. Finally, the coexistence of ultrarelativistic electron butterfly distributions with magnetosonic waves was also observed in the 24 June 2015 storm, providing further support that the magnetosonic waves play a key role in forming butterfly distributions.},
doi = {10.1002/2016JA022370},
journal = {Journal of Geophysical Research. Space Physics},
number = 4,
volume = 121,
place = {United States},
year = {2016},
month = {4}
}