Journal Article

PUBDB-2015-01200

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png High-Energy Gamma-Ray Emission from Solar Flares: Summary of FERMI Large Area Telescope Detections and Analysis of Two M-Class Flares

Ackermann, M.DESY* ; 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, T. J. ; Bregeon, J. ; Brigida, M. ; Bruel, P. ; Buehler, R.DESY* ; Buson, S. ; Caliandro, G. A. ; Cameron, R. A. ; Caraveo, P. A. ; 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, C. D. ; Desiante, R. ; Digel, S. W. ; Di Venere, L. ; do Couto e Silva, E. ; Drell, P. S. ; Drlica-Wagner, A. ; Favuzzi, C. ; Fegan, S. J. ; Focke, W. B. ; 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, I. A. ; Grove, J. E. ; Guiriec, S. ; Hadasch, D. ; Hayashida, M. ; Hays, E. ; Horan, D. ; Hughes, R. E. ; Inoue, Y. ; Jackson, M. S. ; Jogler, T. ; Jóhannesson, G. ; Johnson, W. N. ; Kamae, T. ; Kawano, T. ; Knödlseder, J. ; Kuss, M. ; Lande, J. ; Larsson, S. ; Latronico, L. ; Lemoine-Goumard, M. ; Longo, F. ; Loparco, F. ; Lott, B. ; Lovellette, M. N. ; Lubrano, P. ; Mayer, M. ; Mazziotta, M. N. ; McEnery, J. E. ; Michelson, P. F. ; Mizuno, T. ; Moiseev, A. A. ; Monte, C. ; Monzani, M. E. ; Moretti, E. ; Morselli, A. ; Moskalenko, I. V. ; Murgia, S. ; Murphy, R. ; Nemmen, R. ; Nuss, E. ; Ohno, M. ; Ohsugi, T. ; Okumura, A. ; Omodei, N. ; Orienti, M. ; Orlando, E. ; Ormes, J. F. ; Paneque, D. ; Panetta, J. H. ; Perkins, J. S. ; Pesce-Rollins, M. ; Petrosian, V. ; Piron, F. ; Pivato, G. ; Porter, T. A. ; Rainò, S. ; Rando, R. ; Razzano, M. ; Reimer, A. ; Reimer, O. ; Ritz, S. ; Schulz, A.DESY* ; Sgrò, C. ; Siskind, E. J. ; Spandre, G. ; Spinelli, P. ; Takahashi, H. ; Takeuchi, Y. ; Tanaka, Y. (Corresponding author) ; Thayer, J. G. ; Thayer, J. B. ; Thompson, D. J. ; Tibaldo, L. ; Tinivella, M. ; Tosti, G. ; Troja, E. ; Tronconi, V. ; Usher, T. L. ; Vandenbroucke, J. ; Vasileiou, V. ; Vianello, G. ; Vitale, V. ; Werner, M. ; Winer, B. L. ; Wood, D. L. ; Wood, K. S. ; Wood, M. ; Yang, Z.

2014
Univ.11032 Chicago, Ill. [u.a.]

This record in other databases:        

Please use a persistent id in citations: 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.

Note: (c) The American Astronomical Society

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Contributing Institute(s):

1. Cherenkov Telescope Array (ZEU-CTA)
2. High Energy Steroscopic System (ZEU-HESS)
3. Neutrinoteleskop (ZEU-ICE)

Research Program(s):

1. 523 - High-energy gamma ray astronomy (POF2-523) (POF2-523)
2. P-WIND - New light on the gamma-ray sky: unveiling cosmic-ray accelerators in the Milky Way and their relation to pulsar wind nebulae (259391) (259391)

Experiment(s):

1. No specific instrument

Appears in the scientific report 2014

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Database coverage:
; ; Current Contents - Physical, Chemical and Earth Sciences ; IF >= 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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