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Observation of energetic electrons within magnetic islands

Nature Physics volume 4, pages 19–23 (2008)Cite this article

Abstract

Magnetic reconnection is the underlying process that releases impulsively an enormous amount of magnetic energy1 in solar flares 2,3, flares on strongly magnetized neutron stars4 and substorms in the Earth’s magnetosphere5. Studies of energy release during solar flares, in particular, indicate that up to 50% of the released energy is carried by accelerated 20–100 keV suprathermal electrons6,7,8. How so many electrons can gain so much energy during reconnection has been a long-standing question. A recent theoretical study suggests that volume-filling contracting magnetic islands formed during reconnection can produce a large number of energetic electrons9. Here we report the first evidence of the link between energetic electrons and magnetic islands during reconnection in the Earth’s magnetosphere. The results indicate that energetic electron fluxes peak at sites of compressed density within islands, which imposes a new constraint on theories of electron acceleration.

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Figure 1: Schematic diagrams of magnetic islands in the Earth’s magnetotail.
Figure 2: Association between energetic electron bursts and the signatures of magnetic islands.
Figure 3: Four-spacecraft views of the three largest energetic electron bursts and their corresponding magnetic islands.
Figure 4: Generic features of a magnetic island as seen in Hall magnetohydrodynamic simulations.

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References

  1. Bhattacharjee, A. Impulsive magnetic reconnection in the Earth’s magnetotail and the solar corona. Annu. Rev. Astron. Astrophys. 42, 365–384 (2004).

    Article  ADS  Google Scholar 

  2. Masuda, S., Kosugi, T., Hara, H., Tsuneta, S. & Ogawara, Y. A loop-top hard X-ray source in a compact solar flare as evidence for magnetic reconnection. Nature 371, 495–497 (1994).

    Article  ADS  Google Scholar 

  3. Tsuneta, S. Structure and dynamics of magnetic reconnection in a solar flare. Astrophys. J. 456, 840–849 (1996).

    Article  ADS  Google Scholar 

  4. Hurley, K. et al. An exceptionally bright flare from SGR 180620 and the origins of short-duration big gamma-ray bursts. Nature 434, 1098–1103 (2005).

    Article  ADS  Google Scholar 

  5. Hones, E. W. Jr. Plasma flow in the plasma sheet and its relation to substorms. Radio Sci. 8, 979–990 (1973).

    Article  ADS  Google Scholar 

  6. Lin, R. P. & Hudson, H. S. Nonthermal processes in large solar flares. Sol. Phys. 50, 153–178 (1976).

    Article  ADS  Google Scholar 

  7. Lin, R. P., Krucker, S., Hurford, G. J., Smith, D. M. & Hudson, H. S. RHESSI observations of particle acceleration and energy release in an intense solar gamma-ray line flare. Astrophys. J. 595, L69–L76 (2003).

    Article  ADS  Google Scholar 

  8. Holman, G. D., Linhui, S., Schwartz, R. A. & Emslie, A. G. Electron Bremsstrahlung hard X-ray spectra, electron distributions, and energetics in the 2002 July 23 solar flare. Astrophys. J. 595, L97–L101 (2003).

    Article  ADS  Google Scholar 

  9. Drake, J. F., Swisdak, M., Che, H. & Shay, M. A. Electron acceleration from contracting magnetic islands during reconnection. Nature 443, 553–556 (2006).

    Article  ADS  Google Scholar 

  10. Oieroset, M., Lin, R. P., Phan, T. D., Larson, D. E. & Bale, S. D. Evidence for electron acceleration up to ∼300 keV in the magnetic reconnection diffusion region of Earth’s magnetotail. Phys. Rev. Lett. 89, 195001 (2002).

    Article  ADS  Google Scholar 

  11. Drake, J. F., Shay, M. A. & Thongthai, W. Production of energetic electrons during magnetic reconnection. Phys. Rev. Lett. 94, 095001 (2005).

    Article  ADS  Google Scholar 

  12. Hoshino, M., Mukai, T., Terasawa, T. & Shinohara, I. Suprathermal electron acceleration in magnetic reconnection. J. Geophys. Res. 106, 25979–25997 (2001).

    Article  ADS  Google Scholar 

  13. Pritchett, P. L. Relativistic electron production during driven magnetic reconnection. Geophys. Res. Lett. 33, L13104 (2006).

    Article  ADS  Google Scholar 

  14. Escoubet, C. P., Schmidt, R. & Goldstein, M. L. Cluster—science and mission overview. Space Sci. Rev. 79, 11–32 (1997).

    Article  ADS  Google Scholar 

  15. Kistler, L. M. et al. Contribution of nonadiabatic ions to the cross-tail current in an O+ dominated thin current sheet. J. Geophys. Res. 110, A06213 (2005).

    Article  ADS  Google Scholar 

  16. Ma, Z. W. & Bhattacharjee, A. Sudden disruption of a thin current sheet in collisionless Hall magnetohydrodynamics due to secondary tearing and coalescence instabilities. Geophys. Res. Lett. 26, 3337–3340 (1999).

    Article  ADS  Google Scholar 

  17. Drake, J. F., Swisdak, M., Schoeffler, K. M., Rogers, B. N. & Kobayashi, S. Formation of secondary islands during magnetic reconnection. Geophys. Res. Lett. 33, L13105 (2006).

    Article  ADS  Google Scholar 

  18. Karimabadi, H., Krauss-Verban, D., Omidi, N. & Vu, H. X. Magnetic structure of the reconnection layer and core field generation in plasmoids. J. Geophys. Res. 104, 12313–12326 (1999).

    Article  ADS  Google Scholar 

  19. Chen, L.-J. et al. DC electric fields and electron distribution functions within the diffusion region of magnetotail reconnection: Comparison between Cluster observations and PIC simulations. American Geophysical Union (2006), Fall Meeting.

  20. McKenzie, D. E. & Hudson, H. S. X-ray observations of motions and structure above a solar flare arcade. Astrophys. J. 519, L93–L96 (1999).

    Article  ADS  Google Scholar 

  21. Cattell, C. et al. Cluster observations of electron holes in association with magnetotail reconnection and comparison to simulations. J. Geophys. Res. 110, A01211 (2005).

    Article  ADS  Google Scholar 

  22. Schmitz, H. & Grauer, R. Kinetic Vlasov simulations of collisionless magnetic reconnection. Phys. Plasmas 13, 092309 (2006).

    Article  ADS  Google Scholar 

  23. Yang, H., Jin, S. P. & Zhou, G. C. Density depletion and Hall effect in magnetic reconnection. J. Geophys. Res. 111, A11223 (2006).

    Article  ADS  Google Scholar 

  24. Slavin, J. A. et al. Cluster electric current density measurements within a magnetic flux rope in the plasma sheet. Geophys. Res. Lett. 30, 1362–1365 (2003).

    Article  ADS  Google Scholar 

  25. Pedersen, A. et al. Four-point high time resolution information on electron densities by the electric field measurements (EFW) on Cluster. Ann. Geophys. 19, 1483–1489 (2001).

    Article  ADS  Google Scholar 

  26. Imada, S. et al. Energetic electron acceleration in the downstream reconnection outflow region. J. Geophys. Res. 112, A03202 (2007).

    Article  ADS  Google Scholar 

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Acknowledgements

We thank K. Donahue for her assistance in figure preparation. Research at the UNH was supported by NASA SECGIP04-0025-0171, NSF ATM-0425806 and DoE DE-F902-05ER59832. Research at MPI, Lindau, was supported by DLR grant 50 OC 0003, and that in the UK by PPARC.

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Authors and Affiliations

  1. Space Science Center, University of New Hampshire, Durham, New Hampshire 03824, USA

    L.-J. Chen, A. Bhattacharjee, P. A. Puhl-Quinn, H. Yang & N. Bessho

  2. National Astronomical Observatory of Japan, 2-21-1 Osawa, Tokyo 181-8588, Japan

    S. Imada

  3. Max-Planck-Institute for Solar System Research, D-37191 Katlenburg-Lindau, Germany

    S. Mühlbachler & P. W. Daly

  4. The Blackett Laboratory, Imperial College London, London SW7 2BW, UK

    B. Lefebvre

  5. Swedish Institute of Space Physics, SE-75121 Uppsala, Sweden

    Y. Khotyaintsev & A. Vaivads

  6. Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, RH5 6NT, UK

    A. Fazakerley

  7. Max-Planck-Institute for Extraterrestrial Physics, D-85741 Garching, Germany

    E. Georgescu

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  1. L.-J. Chen
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  2. A. Bhattacharjee
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Contributions

L.-J.C. identified the correlation between energetic electrons and magnetic islands, carried out data analysis and comparison with simulation results and wrote the paper. A.B. oversaw the research project, and facilitated data-simulation comparison. P.A.P.-Q., S.I., S.M., P.W.D., B.L., Y.K., A.V., A.F. and E.G. provided Cluster data and data processing. H.Y. carried out Hall magnetohydrodynamic simulations and N.B. PIC simulations to elucidate kinetic properties of magnetic islands during reconnection. A.B., P.A.P.-Q., H.Y., N.B., S.I. and B.L. discussed the results with L.-J.C., and commented on the paper.

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Correspondence to L.-J. Chen.

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Chen, LJ., Bhattacharjee, A., Puhl-Quinn, P. et al. Observation of energetic electrons within magnetic islands. Nature Phys 4, 19–23 (2008). https://doi.org/10.1038/nphys777

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