HIGH-ENERGY GAMMA-RAY EMISSION FROM SOLAR FLARES: SUMMARY OF FERMI LARGE AREA TELESCOPE DETECTIONS AND ANALYSIS OF TWO M-CLASS FLARES

Ackermann M, Ajello M, Albert A, Allafort A, Baldini L, Barbiellini G, Bastieri D, Bechtol K, Bellazzini R, Bissaldi E, Bonamente E, Bottacini E, Bouvier A, Brandt TJ, Bregeon J, Brigida M, Bruel P, Buehler R, Buson S, Caliandro GA, Cameron RA, Caraveo PA, Cecchi C, Charles E, Chekhtman A, Chen Q, Chiang J, Chiaro G, Ciprini S, Claus R, Cohen-Tanugi J, Conrad J, Cutini S, D'Ammando F, de Angelis A, de Palma F, Dermer CD, Desiante R, Digel SW, Di Venere L, do Couto e Silva E, Drell PS, Drlica-Wagner A, Favuzzi C, Fegan SJ, Focke WB, Franckowiak A, Fukazawa Y, Funk S, Fusco P, Gargano F, Gasparrini D, Germani S, Giglietto N, Giordano F, Giroletti M, Glanzman T, Godfrey G, Grenier IA, Grove JE, Guiriec S, Hadasch D, Hayashida M, Hays E, Horan D, Hughes RE, Inoue Y, Jackson MS, Jogler T, Johannesson G, Johnson WN, Kamae T, Kawano T, Knoedlseder J, Kuss M, Lande J, Larsson S, Latronico L, Lemoine-Goumard M, Longo F, Loparco F, Lott B, Lovellette MN, Lubrano P, Mayer M, Mazziotta MN, McEnery JE, Michelson PF, Mizuno T, Moiseev AA, Monte C, Monzani ME, Moretti E, Morselli A, Moskalenko IV, Murgia S, Murphy R, Nemmen R, Nuss E, Ohno M, Ohsugi T, Okumura A, Omodei N, Orienti M, Orlando E, Ormes JF, Paneque D, Panetta JH, Perkins JS, Pesce-Rollins M, Petrosian V, Piron F, Pivato G, Porter TA, Raino S, Rando R, Razzano M, Reimer A, Reimer O, Ritz S, Schulz A, Sgro C, Siskind EJ, Spandre G, Spinelli P, Takahashi H, Takeuchi Y, Tanaka Y, Thayer JG, Thayer JB, Thompson DJ, Tibaldo L, Tinivella M, Tosti G, Troja E, Tronconi V, Usher TL, Vandenbroucke J, Vasileiou V, Vianello G, Vitale V, Werner M, Winer BL, Wood DL, Wood KS, Wood M, Yang Z (2014)

Publication Status: Published

Publication Type: Journal article

Publication year: 2014

Journal

Publisher: American Astronomical Society

Book Volume: 787

DOI: 10.1088/0004-637X/787/1/15

Abstract

We present the detections of 18 solar flares detected in high-energy gamma-rays (above 100 MeV) with the Fermi Large Area Telescope (LAT) during its first 4 yr of operation. This work suggests that particle acceleration up to very high energies in solar flares is more common than previously thought, occurring even in modest flares, and for longer durations. Interestingly, all these flares are associated with fairly fast coronal mass ejections (CMEs). We then describe the detailed temporal, spatial, and spectral characteristics of the first two long-lasting events: the 2011 March 7 flare, a moderate (M3.7) impulsive flare followed by slowly varying gamma-ray emission over 13 hr, and the 2011 June 7 M2.5 flare, which was followed by gamma-ray emission lasting for 2 hr. We compare the Fermi LAT data with X-ray and proton data measurements from GOES and RHESSI. We argue that the gamma-rays are more likely produced through pion decay than electron bremsstrahlung, and we find that the energy spectrum of the proton distribution softens during the extended emission of the 2011 March 7 flare. This would disfavor a trapping scenario for particles accelerated during the impulsive phase of the flare and point to a continuous acceleration process at play for the duration of the flares. CME shocks are known for accelerating the solar energetic particles (SEPs) observed in situ on similar timescales, but it might be challenging to explain the production of gamma-rays at the surface of the Sun while the CME is halfway to the Earth. A stochastic turbulence acceleration process occurring in the solar corona is another likely scenario. Detailed comparison of characteristics of SEPs and gamma-ray-emitting particles for several flares will be helpful to distinguish between these two possibilities.

Authors with CRIS profile

Involved external institutions

Stockholm University / Stockholms universitet Sweden (SE) University of Bari Aldo Moro / Università degli Studi di Bari Aldo Moro Italy (IT) Université Bordeaux 1, Sciences et Technologies France (FR) Ohio State University United States (USA) (US) Leopold-Franzens-Universität Innsbruck / University of Innsbruck Austria (AT) Stanford University United States (USA) (US) National Institute for Nuclear Physics / Istituto Nazionale di Fisica Nucleare (INFN) Italy (IT) Spanish National Research Council / Consejo Superior de Investigaciones Científicas (CSIC) Spain (ES) Italian Space Agency / Agenzia Spaziale Italiana (ASI) Italy (IT) National Institute for Astrophysics / Istituto Nazionale Astrofisica (INAF) Italy (IT) University of Udine / Università degli Studi di Udine Italy (IT) École Polytechnique - Université Paris-Saclay France (FR) Hiroshima University Japan (JP) National Aeronautics and Space Administration (NASA) United States (USA) (US) AlbaNova University Centre / Kungliga Tekniska Högskolan AlbaNova Universitetscentrum Sweden (SE) U.S. Naval Research Laboratory United States (USA) (US) Japan Aerospace eXploration Agency (JAXA) Japan (JP) Waseda University / 早稲田大学 Japan (JP) University of Padua / Universita degli Studi di Padova Italy (IT) Praxis, Inc. United States (USA) (US) University of Montpellier / Université Montpellier France (FR) Deutsches Elektronen-Synchrotron DESY Germany (DE) University of California Santa Cruz United States (USA) (US) National Center for Scientific Research / Centre national de la recherche scientifique (CNRS) France (FR) NYCB Real-Time Computing, Inc. United States (USA) (US) University of Pisa / Università di Pisa (UniPi) Italy (IT) University of California, Berkeley United States (USA) (US) University of Iceland (UI) / Háskóli Íslands Iceland (IS) George Mason University United States (USA) (US) University of Denver United States (USA) (US) University of Paris 7 - Denis Diderot / Université Paris VII Denis Diderot France (FR)

How to cite

APA:

Ackermann, M., Ajello, M., Albert, A., Allafort, A., Baldini, L., Barbiellini, G.,... Yang, Z. (2014). HIGH-ENERGY GAMMA-RAY EMISSION FROM SOLAR FLARES: SUMMARY OF FERMI LARGE AREA TELESCOPE DETECTIONS AND ANALYSIS OF TWO M-CLASS FLARES. Astrophysical Journal, 787. https://dx.doi.org/10.1088/0004-637X/787/1/15

MLA:

Ackermann, M., et al. "HIGH-ENERGY GAMMA-RAY EMISSION FROM SOLAR FLARES: SUMMARY OF FERMI LARGE AREA TELESCOPE DETECTIONS AND ANALYSIS OF TWO M-CLASS FLARES." Astrophysical Journal 787 (2014).

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