Letter abstract
Nature Physics 4, 19 - 23 (2008)
Published online: 11 November 2007 | doi:10.1038/nphys777
Subject Categories: Astrophysics | Plasma physics
Observation of energetic electrons within magnetic islands
L.-J. Chen1, A. Bhattacharjee1, P. A. Puhl-Quinn1, H. Yang1, N. Bessho1, S. Imada2, S. Mühlbachler3, P. W. Daly3, B. Lefebvre4, Y. Khotyaintsev5, A. Vaivads5, A. Fazakerley6 & E. Georgescu7
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.
- Space Science Center, University of New Hampshire, Durham, New Hampshire 03824, USA
- National Astronomical Observatory of Japan, 2-21-1 Osawa, Tokyo 181-8588, Japan
- Max-Planck-Institute for Solar System Research, D-37191 Katlenburg-Lindau, Germany
- The Blackett Laboratory, Imperial College London, London SW7 2BW, UK
- Swedish Institute of Space Physics, SE-75121 Uppsala, Sweden
- Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT, UK
- Max-Planck-Institute for Extraterrestrial Physics, D-85741 Garching, Germany
Correspondence to: L.-J. Chen1 e-mail: lijen@mailaps.org
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