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Title: High-energy gamma-ray emission from solar flares: Summary of Fermi large area telescope detections and analysis of two m-class flares

Here, we present the detections of 18 solar flares detected in high-energy γ-rays (above 100 MeV) with the Fermi Large Area Telescope (LAT) during its first 4 yr of operation. Our 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 γ-ray emission over 13 hr, and the 2011 June 7 M2.5 flare, which was followed by γ-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 γ-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. Furthermore, this would disfavor a trapping scenario for particles accelerated during the impulsive phase of the flare and point to a continuous accelerationmore » 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 γ-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 γ-ray-emitting particles for several flares will be helpful to distinguish between these two possibilities.« less
Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »; ; ; ; ; ; ; ; ; ; ; ; ; ; ORCiD logo ; ; ; ORCiD logo ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ORCiD logo ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; « less
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 787; Journal Issue: 1; Journal ID: ISSN 0004-637X
Publisher:
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Contributing Orgs:
Fermi LAT Collaboration
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; sun: flares; sun: x-rays; gamma rays
OSTI Identifier:
1356527

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, T. J., Bregeon, J., Brigida, M., Bruel, P., Buehler, R., 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., Sgrò, C., Siskind, E. J., Spandre, G., Spinelli, P., Takahashi, H., Takeuchi, Y., Tanaka, Y., 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., and Yang, Z.. High-energy gamma-ray emission from solar flares: Summary of Fermi large area telescope detections and analysis of two m-class flares. United States: N. p., Web. doi:10.1088/0004-637X/787/1/15.
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, T. J., Bregeon, J., Brigida, M., Bruel, P., Buehler, R., 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., Sgrò, C., Siskind, E. J., Spandre, G., Spinelli, P., Takahashi, H., Takeuchi, Y., Tanaka, Y., 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.. High-energy gamma-ray emission from solar flares: Summary of Fermi large area telescope detections and analysis of two m-class flares. United States. doi:10.1088/0004-637X/787/1/15.
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, T. J., Bregeon, J., Brigida, M., Bruel, P., Buehler, R., 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., Sgrò, C., Siskind, E. J., Spandre, G., Spinelli, P., Takahashi, H., Takeuchi, Y., Tanaka, Y., 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., and 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". United States. doi:10.1088/0004-637X/787/1/15. https://www.osti.gov/servlets/purl/1356527.
@article{osti_1356527,
title = {High-energy gamma-ray emission from solar flares: Summary of Fermi large area telescope detections and analysis of two m-class flares},
author = {Ackermann, M. and Ajello, M. and Albert, A. and Allafort, A. and Baldini, L. and Barbiellini, G. and Bastieri, D. and Bechtol, K. and Bellazzini, R. and Bissaldi, E. and Bonamente, E. and Bottacini, E. and Bouvier, A. and Brandt, T. J. and Bregeon, J. and Brigida, M. and Bruel, P. and Buehler, R. and Buson, S. and Caliandro, G. A. and Cameron, R. A. and Caraveo, P. A. and Cecchi, C. and Charles, E. and Chekhtman, A. and Chen, Q. and Chiang, J. and Chiaro, G. and Ciprini, S. and Claus, R. and Cohen-Tanugi, J. and Conrad, J. and Cutini, S. and D'Ammando, F. and de Angelis, A. and de Palma, F. and Dermer, C. D. and Desiante, R. and Digel, S. W. and Di Venere, L. and do Couto e Silva, E. and Drell, P. S. and Drlica-Wagner, A. and Favuzzi, C. and Fegan, S. J. and Focke, W. B. and Franckowiak, A. and Fukazawa, Y. and Funk, S. and Fusco, P. and Gargano, F. and Gasparrini, D. and Germani, S. and Giglietto, N. and Giordano, F. and Giroletti, M. and Glanzman, T. and Godfrey, G. and Grenier, I. A. and Grove, J. E. and Guiriec, S. and Hadasch, D. and Hayashida, M. and Hays, E. and Horan, D. and Hughes, R. E. and Inoue, Y. and Jackson, M. S. and Jogler, T. and Jóhannesson, G. and Johnson, W. N. and Kamae, T. and Kawano, T. and Knödlseder, J. and Kuss, M. and Lande, J. and Larsson, S. and Latronico, L. and Lemoine-Goumard, M. and Longo, F. and Loparco, F. and Lott, B. and Lovellette, M. N. and Lubrano, P. and Mayer, M. and Mazziotta, M. N. and McEnery, J. E. and Michelson, P. F. and Mizuno, T. and Moiseev, A. A. and Monte, C. and Monzani, M. E. and Moretti, E. and Morselli, A. and Moskalenko, I. V. and Murgia, S. and Murphy, R. and Nemmen, R. and Nuss, E. and Ohno, M. and Ohsugi, T. and Okumura, A. and Omodei, N. and Orienti, M. and Orlando, E. and Ormes, J. F. and Paneque, D. and Panetta, J. H. and Perkins, J. S. and Pesce-Rollins, M. and Petrosian, V. and Piron, F. and Pivato, G. and Porter, T. A. and Rainò, S. and Rando, R. and Razzano, M. and Reimer, A. and Reimer, O. and Ritz, S. and Schulz, A. and Sgrò, C. and Siskind, E. J. and Spandre, G. and Spinelli, P. and Takahashi, H. and Takeuchi, Y. and Tanaka, Y. and Thayer, J. G. and Thayer, J. B. and Thompson, D. J. and Tibaldo, L. and Tinivella, M. and Tosti, G. and Troja, E. and Tronconi, V. and Usher, T. L. and Vandenbroucke, J. and Vasileiou, V. and Vianello, G. and Vitale, V. and Werner, M. and Winer, B. L. and Wood, D. L. and Wood, K. S. and Wood, M. and Yang, Z.},
abstractNote = {Here, we present the detections of 18 solar flares detected in high-energy γ-rays (above 100 MeV) with the Fermi Large Area Telescope (LAT) during its first 4 yr of operation. Our 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 γ-ray emission over 13 hr, and the 2011 June 7 M2.5 flare, which was followed by γ-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 γ-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. Furthermore, 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 γ-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 γ-ray-emitting particles for several flares will be helpful to distinguish between these two possibilities.},
doi = {10.1088/0004-637X/787/1/15},
journal = {Astrophysical Journal},
number = 1,
volume = 787,
place = {United States},
year = {2014},
month = {4}
}