University of Oulu

Kocharov, L., Omodei, N., Mishev, A., Pesce-Rollins, M., Longo, F., Yu, S., Gary, D. E., Vainio, R., & Usoskin, I. (2021). Multiple Sources of Solar High-energy Protons. The Astrophysical Journal, 915(1), 12.

Multiple sources of solar high-energy protons

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Author: Kocharov, Leon1,2; Omodei, Nicola3; Mishev, Alexander1,2;
Organizations: 1Space Physics and Astronomy Research Unit, Faculty of Sciences, P.O.B. 3000, Oulu FI-90014, Finland
2Sodankylä Geophysical Observatory, University of Oulu, Oulu FI-90014, Finland
3W.W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USA
4Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, Italy
5Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste, Italy
6Dipartimento di Fisica, Università di Trieste, I-34127 Trieste, Italy
7Center for Solar-Terrestrial Research, New Jersey Institute of Technology, Newark, NJ 07102-1982, USA
8Space Research Laboratory, Department of Physics and Astronomy, University of Turku, Turku FI-20014, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.8 MB)
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Language: English
Published: IOP Publishing, 2021
Publish Date: 2021-07-01


During the 24th solar cycle, the Fermi Large Area Telescope (LAT) has observed a total of 27 solar flares possessing delayed γ-ray emission, including the exceptionally well-observed flare and coronal mass ejection (CME) on 2017 September 10. Based on the Fermi/LAT data, we plot, for the first time, maps of possible sources of the delayed >100 MeV γ-ray emission of the 2017 September 10 event. The long-lasting γ-ray emission is localized under the CME core. The γ-ray spectrum exhibits intermittent changes in time, implying that more than one source of high-energy protons was formed during the flare–CME eruption. We find a good statistical correlation between the γ-ray fluences of the Fermi/LAT-observed delayed events and the products of corresponding CME speed and the square root of the soft X-ray flare magnitude. Data support the idea that both flares and CMEs jointly contribute to the production of subrelativistic and relativistic protons near the Sun.

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Series: Astrophysical journal
ISSN: 0004-637X
ISSN-E: 1538-4357
ISSN-L: 0004-637X
Volume: 915
Issue: 1
Article number: 12
DOI: 10.3847/1538-4357/abff57
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: This research is supported by the Academy of Finland at University of Oulu (projects 330064 QUASARE and 321882 ESPERA). D.G. and S.U. acknowledge support from NSF grant AST-1910354 and NASA grant 80NSSC18K1128 to New Jersey Institute of Technology.
Academy of Finland Grant Number: 330064
Detailed Information: 330064 (Academy of Finland Funding decision)
321882 (Academy of Finland Funding decision)
Copyright information: © 2021. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.