Flat Proton Spectra in Large Solar Energetic Particle Events

D. Lario, L. Berger, L. B.I.I.I. Wilson, R. B. Decker, D. K. Haggerty, E. C. Roelof, R. F. Wimmer-Schweingruber, J. Giacalone

Research output: Contribution to journalConference articlepeer-review

11 Scopus citations


We present solar energetic particle events observed at 1 AU from the Sun for which the proton energy spectra at energies between ∼50 keV to ∼1 MeV flatten during a period of at least ∼12 hours prior to the passage of the associated interplanetary shock. The flattening of the proton energy spectra occurs when the source of the particles (presumably the traveling interplanetary shock) is still downwind from the spacecraft and particle intensities are still continuously increasing. The arrival of the shock at the spacecraft is then characterized by a steepening of the spectra, where low-energy proton intensities show a more pronounced enhancement than the high-energy proton intensities. We discuss the mechanisms that may result in this flattening of the spectra in terms of current models presented in the literature.

Original languageEnglish (US)
Article number012014
JournalJournal of Physics: Conference Series
Issue number1
StatePublished - Oct 24 2018
Event17th Annual International Astrophysics Conference, AIAC 2018 - Santa Fe, United States
Duration: Mar 5 2018Mar 9 2018

ASJC Scopus subject areas

  • General Physics and Astronomy


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