Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares

M. Ackermann; A. Allafort; L. Baldini; G. Barbiellini; D. Bastieri; R. Bellazzini; E. Bissaldi; R. Bonino; E. Bottacini; J. Bregeon; P. Bruel; R. Buehler; R. A. Cameron; M. Caragiulo; P. A. Caraveo; E. Cavazzuti; C. Cecchi; E. Charles; S. Ciprini; F. Costanza; S. Cutini; F. D'Ammando; F. De Palma; R. Desiante; S. W. Digel; N. Di Lalla; M. Di Mauro; L. Di Venere; P. S. Drell; C. Favuzzi; Y. Fukazawa; P. Fusco; F. Gargano; N. Giglietto; F. Giordano; M. Giroletti; I. A. Grenier; L. Guillemot; S. Guiriec; T. Jogler; G. Jóhannesson; L. Kashapova; S. Krucker; M. Kuss; G. La Mura; S. Larsson; L. Latronico; J. Li; W. Liu; F. Longo; F. Loparco; P. Lubrano; J. D. Magill; S. Maldera; A. Manfreda; M. N. Mazziotta; W. Mitthumsiri; T. Mizuno; M. E. Monzani; A. Morselli; I. V. Moskalenko; M. Negro; E. Nuss; T. Ohsugi; N. Omodei; E. Orlando; V. Pal'Shin; D. Paneque; J. S. Perkins; M. Pesce-Rollins; V. Petrosian; F. Piron; G. Principe; S. Rainò; R. Rando; M. Razzano; O. Reimer; F. Rubio Da Costa; C. Sgrò; D. Simone; E. J. Siskind; F. Spada; G. Spandre; P. Spinelli; H. Tajima; J. B. Thayer; D. F. Torres; E. Troja; G. Vianello

doi:10.3847/1538-4357/835/2/219

Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares

M. Ackermann, A. Allafort, L. Baldini, G. Barbiellini, D. Bastieri, R. Bellazzini, E. Bissaldi, R. Bonino, E. Bottacini, J. Bregeon, P. Bruel, R. Buehler, R. A. Cameron, M. Caragiulo, P. A. Caraveo, E. Cavazzuti, C. Cecchi, E. Charles, S. Ciprini, F. CostanzaS. Cutini, F. D'Ammando, F. De Palma, R. Desiante, S. W. Digel, N. Di Lalla, M. Di Mauro, L. Di Venere, P. S. Drell, C. Favuzzi, Y. Fukazawa, P. Fusco, F. Gargano, N. Giglietto, F. Giordano, M. Giroletti, I. A. Grenier, L. Guillemot, S. Guiriec, T. Jogler, G. Jóhannesson, L. Kashapova, S. Krucker, M. Kuss, G. La Mura, S. Larsson, L. Latronico, J. Li, W. Liu, F. Longo, F. Loparco, P. Lubrano, J. D. Magill, S. Maldera, A. Manfreda, M. N. Mazziotta, W. Mitthumsiri, T. Mizuno, M. E. Monzani, A. Morselli, I. V. Moskalenko, M. Negro, E. Nuss, T. Ohsugi, N. Omodei, E. Orlando, V. Pal'Shin, D. Paneque, J. S. Perkins, M. Pesce-Rollins, V. Petrosian, F. Piron, G. Principe, S. Rainò, R. Rando, M. Razzano, O. Reimer, F. Rubio Da Costa, C. Sgrò, D. Simone, E. J. Siskind, F. Spada, G. Spandre, P. Spinelli, H. Tajima, J. B. Thayer, D. F. Torres, E. Troja, G. Vianello

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Abstract

© 2017. The American Astronomical Society. All rights reserved. We report on the Fermi-LAT detection of high-energy emission from the behind-the-limb (BTL) solar flares that occurred on 2013 October 11, and 2014 January 6 and September 1. The Fermi-LAT observations are associated with flares from active regions originating behind both the eastern and western limbs, as determined by STEREO. All three flares are associated with very fast coronal mass ejections (CMEs) and strong solar energetic particle events. We present updated localizations of the >100 MeV photon emission, hard X-ray (HXR) and EUV images, and broadband spectra from 10 keV to 10 GeV, as well as microwave spectra. We also provide a comparison of the BTL flares detected by Fermi-LAT with three on-disk flares and present a study of some of the significant quantities of these flares as an attempt to better understand the acceleration mechanisms at work during these occulted flares. We interpret the HXR emission to be due to electron bremsstrahlung from a coronal thin-target loop top with the accelerated electron spectra steepening at semirelativistic energies. The >100 MeV gamma-rays are best described by a pion-decay model resulting from the interaction of protons (and other ions) in a thick-target photospheric source. The protons are believed to have been accelerated (to energies >10 GeV) in the CME environment and precipitate down to the photosphere from the downstream side of the CME shock and landed on the front side of the Sun, away from the original flare site and the HXR emission.

Original language	English
Article number	219
Journal	Astrophysical Journal
Volume	835
Issue number	2
DOIs	https://doi.org/10.3847/1538-4357/835/2/219
Publication status	Published - 1 Feb 2017

Keywords

Sun: flares
Sun: X-rays, gamma rays

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10.3847/1538-4357/835/2/219

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Ackermann, M., Allafort, A., Baldini, L., Barbiellini, G., Bastieri, D., Bellazzini, R., Bissaldi, E., Bonino, R., Bottacini, E., Bregeon, J., Bruel, P., Buehler, R., Cameron, R. A., Caragiulo, M., Caraveo, P. A., Cavazzuti, E., Cecchi, C., Charles, E., Ciprini, S., ... Vianello, G. (2017). Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares. Astrophysical Journal, 835(2), [219]. https://doi.org/10.3847/1538-4357/835/2/219

@article{a47d676a570c4860bcb0759d0ff039bb,

title = "Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares",

abstract = "{\textcopyright} 2017. The American Astronomical Society. All rights reserved. We report on the Fermi-LAT detection of high-energy emission from the behind-the-limb (BTL) solar flares that occurred on 2013 October 11, and 2014 January 6 and September 1. The Fermi-LAT observations are associated with flares from active regions originating behind both the eastern and western limbs, as determined by STEREO. All three flares are associated with very fast coronal mass ejections (CMEs) and strong solar energetic particle events. We present updated localizations of the >100 MeV photon emission, hard X-ray (HXR) and EUV images, and broadband spectra from 10 keV to 10 GeV, as well as microwave spectra. We also provide a comparison of the BTL flares detected by Fermi-LAT with three on-disk flares and present a study of some of the significant quantities of these flares as an attempt to better understand the acceleration mechanisms at work during these occulted flares. We interpret the HXR emission to be due to electron bremsstrahlung from a coronal thin-target loop top with the accelerated electron spectra steepening at semirelativistic energies. The >100 MeV gamma-rays are best described by a pion-decay model resulting from the interaction of protons (and other ions) in a thick-target photospheric source. The protons are believed to have been accelerated (to energies >10 GeV) in the CME environment and precipitate down to the photosphere from the downstream side of the CME shock and landed on the front side of the Sun, away from the original flare site and the HXR emission.",

keywords = "Sun: flares, Sun: X-rays, gamma rays",

author = "M. Ackermann and A. Allafort and L. Baldini and G. Barbiellini and D. Bastieri and R. Bellazzini and E. Bissaldi and R. Bonino and E. Bottacini and J. Bregeon and P. Bruel and R. Buehler and Cameron, {R. A.} and M. Caragiulo and Caraveo, {P. A.} and E. Cavazzuti and C. Cecchi and E. Charles and S. Ciprini and F. Costanza and S. Cutini and F. D'Ammando and Palma, {F. De} and R. Desiante and Digel, {S. W.} and Lalla, {N. Di} and Mauro, {M. Di} and Venere, {L. Di} and Drell, {P. S.} and C. Favuzzi and Y. Fukazawa and P. Fusco and F. Gargano and N. Giglietto and F. Giordano and M. Giroletti and Grenier, {I. A.} and L. Guillemot and S. Guiriec and T. Jogler and G. J{\'o}hannesson and L. Kashapova and S. Krucker and M. Kuss and Mura, {G. La} and S. Larsson and L. Latronico and J. Li and W. Liu and F. Longo and F. Loparco and P. Lubrano and Magill, {J. D.} and S. Maldera and A. Manfreda and Mazziotta, {M. N.} and W. Mitthumsiri and T. Mizuno and Monzani, {M. E.} and A. Morselli and Moskalenko, {I. V.} and M. Negro and E. Nuss and T. Ohsugi and N. Omodei and E. Orlando and V. Pal'Shin and D. Paneque and Perkins, {J. S.} and M. Pesce-Rollins and V. Petrosian and F. Piron and G. Principe and S. Rain{\`o} and R. Rando and M. Razzano and O. Reimer and Costa, {F. Rubio Da} and C. Sgr{\`o} and D. Simone and Siskind, {E. J.} and F. Spada and G. Spandre and P. Spinelli and H. Tajima and Thayer, {J. B.} and Torres, {D. F.} and E. Troja and G. Vianello",

year = "2017",

month = feb,

day = "1",

doi = "10.3847/1538-4357/835/2/219",

language = "English",

volume = "835",

journal = "Astrophysical Journal",

issn = "0004-637X",

number = "2",

}

Ackermann, M, Allafort, A, Baldini, L, Barbiellini, G, Bastieri, D, Bellazzini, R, Bissaldi, E, Bonino, R, Bottacini, E, Bregeon, J, Bruel, P, Buehler, R, Cameron, RA, Caragiulo, M, Caraveo, PA, Cavazzuti, E, Cecchi, C, Charles, E, Ciprini, S, Costanza, F, Cutini, S, D'Ammando, F, Palma, FD, Desiante, R, Digel, SW, Lalla, ND, Mauro, MD, Venere, LD, Drell, PS, Favuzzi, C, Fukazawa, Y, Fusco, P, Gargano, F, Giglietto, N, Giordano, F, Giroletti, M, Grenier, IA, Guillemot, L, Guiriec, S, Jogler, T, Jóhannesson, G, Kashapova, L, Krucker, S, Kuss, M, Mura, GL, Larsson, S, Latronico, L, Li, J, Liu, W, Longo, F, Loparco, F, Lubrano, P, Magill, JD, Maldera, S, Manfreda, A, Mazziotta, MN, Mitthumsiri, W, Mizuno, T, Monzani, ME, Morselli, A, Moskalenko, IV, Negro, M, Nuss, E, Ohsugi, T, Omodei, N, Orlando, E, Pal'Shin, V, Paneque, D, Perkins, JS, Pesce-Rollins, M, Petrosian, V, Piron, F, Principe, G, Rainò, S, Rando, R, Razzano, M, Reimer, O, Costa, FRD, Sgrò, C, Simone, D, Siskind, EJ, Spada, F, Spandre, G, Spinelli, P, Tajima, H, Thayer, JB, Torres, DF, Troja, E & Vianello, G 2017, 'Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares', Astrophysical Journal, vol. 835, no. 2, 219. https://doi.org/10.3847/1538-4357/835/2/219

TY - JOUR

T1 - Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares

AU - Ackermann, M.

AU - Allafort, A.

AU - Baldini, L.

AU - Barbiellini, G.

AU - Bastieri, D.

AU - Bellazzini, R.

AU - Bissaldi, E.

AU - Bonino, R.

AU - Bottacini, E.

AU - Bregeon, J.

AU - Bruel, P.

AU - Buehler, R.

AU - Cameron, R. A.

AU - Caragiulo, M.

AU - Caraveo, P. A.

AU - Cavazzuti, E.

AU - Cecchi, C.

AU - Charles, E.

AU - Ciprini, S.

AU - Costanza, F.

AU - Cutini, S.

AU - D'Ammando, F.

AU - Palma, F. De

AU - Desiante, R.

AU - Digel, S. W.

AU - Lalla, N. Di

AU - Mauro, M. Di

AU - Venere, L. Di

AU - Drell, P. S.

AU - Favuzzi, C.

AU - Fukazawa, Y.

AU - Fusco, P.

AU - Gargano, F.

AU - Giglietto, N.

AU - Giordano, F.

AU - Giroletti, M.

AU - Grenier, I. A.

AU - Guillemot, L.

AU - Guiriec, S.

AU - Jogler, T.

AU - Jóhannesson, G.

AU - Kashapova, L.

AU - Krucker, S.

AU - Kuss, M.

AU - Mura, G. La

AU - Larsson, S.

AU - Latronico, L.

AU - Li, J.

AU - Liu, W.

AU - Longo, F.

AU - Loparco, F.

AU - Lubrano, P.

AU - Magill, J. D.

AU - Maldera, S.

AU - Manfreda, A.

AU - Mazziotta, M. N.

AU - Mitthumsiri, W.

AU - Mizuno, T.

AU - Monzani, M. E.

AU - Morselli, A.

AU - Moskalenko, I. V.

AU - Negro, M.

AU - Nuss, E.

AU - Ohsugi, T.

AU - Omodei, N.

AU - Orlando, E.

AU - Pal'Shin, V.

AU - Paneque, D.

AU - Perkins, J. S.

AU - Pesce-Rollins, M.

AU - Petrosian, V.

AU - Piron, F.

AU - Principe, G.

AU - Rainò, S.

AU - Rando, R.

AU - Razzano, M.

AU - Reimer, O.

AU - Costa, F. Rubio Da

AU - Sgrò, C.

AU - Simone, D.

AU - Siskind, E. J.

AU - Spada, F.

AU - Spandre, G.

AU - Spinelli, P.

AU - Tajima, H.

AU - Thayer, J. B.

AU - Torres, D. F.

AU - Troja, E.

AU - Vianello, G.

PY - 2017/2/1

Y1 - 2017/2/1

N2 - © 2017. The American Astronomical Society. All rights reserved. We report on the Fermi-LAT detection of high-energy emission from the behind-the-limb (BTL) solar flares that occurred on 2013 October 11, and 2014 January 6 and September 1. The Fermi-LAT observations are associated with flares from active regions originating behind both the eastern and western limbs, as determined by STEREO. All three flares are associated with very fast coronal mass ejections (CMEs) and strong solar energetic particle events. We present updated localizations of the >100 MeV photon emission, hard X-ray (HXR) and EUV images, and broadband spectra from 10 keV to 10 GeV, as well as microwave spectra. We also provide a comparison of the BTL flares detected by Fermi-LAT with three on-disk flares and present a study of some of the significant quantities of these flares as an attempt to better understand the acceleration mechanisms at work during these occulted flares. We interpret the HXR emission to be due to electron bremsstrahlung from a coronal thin-target loop top with the accelerated electron spectra steepening at semirelativistic energies. The >100 MeV gamma-rays are best described by a pion-decay model resulting from the interaction of protons (and other ions) in a thick-target photospheric source. The protons are believed to have been accelerated (to energies >10 GeV) in the CME environment and precipitate down to the photosphere from the downstream side of the CME shock and landed on the front side of the Sun, away from the original flare site and the HXR emission.

AB - © 2017. The American Astronomical Society. All rights reserved. We report on the Fermi-LAT detection of high-energy emission from the behind-the-limb (BTL) solar flares that occurred on 2013 October 11, and 2014 January 6 and September 1. The Fermi-LAT observations are associated with flares from active regions originating behind both the eastern and western limbs, as determined by STEREO. All three flares are associated with very fast coronal mass ejections (CMEs) and strong solar energetic particle events. We present updated localizations of the >100 MeV photon emission, hard X-ray (HXR) and EUV images, and broadband spectra from 10 keV to 10 GeV, as well as microwave spectra. We also provide a comparison of the BTL flares detected by Fermi-LAT with three on-disk flares and present a study of some of the significant quantities of these flares as an attempt to better understand the acceleration mechanisms at work during these occulted flares. We interpret the HXR emission to be due to electron bremsstrahlung from a coronal thin-target loop top with the accelerated electron spectra steepening at semirelativistic energies. The >100 MeV gamma-rays are best described by a pion-decay model resulting from the interaction of protons (and other ions) in a thick-target photospheric source. The protons are believed to have been accelerated (to energies >10 GeV) in the CME environment and precipitate down to the photosphere from the downstream side of the CME shock and landed on the front side of the Sun, away from the original flare site and the HXR emission.

KW - Sun: flares

KW - Sun: X-rays, gamma rays

U2 - 10.3847/1538-4357/835/2/219

DO - 10.3847/1538-4357/835/2/219

M3 - Article

SN - 0004-637X

VL - 835

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 219

ER -

Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares

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