Fermi large area telescope observations of two gamma-ray emission components from the quiescent sun

A. A. Abdo, M. Ackermann, M. Ajello, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, K. Bechtol, R. Bellazzini, B. Berenji, E. Bonamente, A. W. Borgland, A. Bouvier, J. Bregeon, A. Brez, M. Brigida, P. Bruel, R. Buehler, S. Buson, G. A. Caliandro & 130 others R. A. Cameron, P. A. Caraveo, J. M. Casandjian, C. Cecchi, E. Charles, A. Chekhtman, J. Chiang, S. Ciprini, R. Claus, J. Cohen-Tanugi, J. Conrad, S. Cutini, A. De Angelis, F. De Palma, C. D. Dermer, S. W. Digel, E. Do Couto E Silva, P. S. Drell, R. Dubois, C. Favuzzi, S. J. Fegan, W. B. Focke, P. Fortin, M. Frailis, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Gehrels, S. Germani, N. Giglietto, F. Giordano, M. Giroletti, T. Glanzman, G. Godfrey, I. A. Grenier, L. Grillo, S. Guiriec, D. Hadasch, E. Hays, R. E. Hughes, G. Iafrate, G. Jóhannesson, A. S. Johnson, T. J. Johnson, T. Kamae, H. Katagiri, Jun Kataoka, J. Knödlseder, M. Kuss, J. Lande, L. Latronico, S. H. Lee, A. M. Lionetto, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, A. Makeev, M. N. Mazziotta, J. E. McEnery, J. Mehault, P. F. Michelson, W. Mitthumsiri, T. Mizuno, A. A. Moiseev, C. Monte, M. E. Monzani, A. Morselli, I. V. Moskalenko, S. Murgia, T. Nakamori, M. Naumann-Godo, P. L. Nolan, J. P. Norris, E. Nuss, T. Ohsugi, A. Okumura, N. Omodei, E. Orlando, J. F. Ormes, M. Ozaki, D. Paneque, V. Pelassa, M. Pesce-Rollins, M. Pierbattista, F. Piron, T. A. Porter, S. Rainò, R. Rando, M. Razzano, A. Reimer, O. Reimer, T. Reposeur, S. Ritz, H. F W Sadrozinski, T. L. Schalk, C. Sgrò, G. H. Share, E. J. Siskind, P. D. Smith, G. Spandre, P. Spinelli, M. S. Strickman, A. W. Strong, H. Takahashi, T. Tanaka, J. G. Thayer, J. B. Thayer, D. J. Thompson, L. Tibaldo, D. F. Torres, G. Tosti, A. Tramacere, E. Troja, Y. Uchiyama, T. L. Usher, J. Vandenbroucke, V. Vasileiou, G. Vianello, N. Vilchez, V. Vitale, A. E. Vladimirov, A. P. Waite, P. Wang, B. L. Winer, K. S. Wood, Z. Yang, M. Ziegler

    Research output: Contribution to journalArticle

    64 Citations (Scopus)

    Abstract

    We report the detection of high-energy γ-rays from the quiescent Sun with the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope (Fermi) during the first 18 months of the mission. These observations correspond to the recent period of low solar activity when the emission induced by cosmic rays (CRs) is brightest. For the first time, the high statistical significance of the observations allows clear separation of the two components: the point-like emission from the solar disk due to CR cascades in the solar atmosphere and extended emission from the inverse Compton (IC) scattering of CR electrons on solar photons in the heliosphere. The observed integral flux (≥100MeV) from the solar disk is (4.6 ± 0.2[statistical error] +1.0 - 0.8[systematic error]) × 10 -7cm-2s-1, which is 7 times higher than predicted by the "nominal" model of Seckel etal. In contrast, the observed integral flux (≥100MeV) of the extended emission from a region of 20° radius centered on the Sun, but excluding the disk itself, (6.8 ± 0.7[stat.]+0.5 - 0.4[syst.]) × 10 -7cm-2s-1, along with the observed spectrum and the angular profile, is in good agreement with the theoretical predictions for the IC emission.

    Original languageEnglish
    Article number116
    JournalAstrophysical Journal
    Volume734
    Issue number2
    DOIs
    Publication statusPublished - 2011 Jun 10

    Fingerprint

    sun
    gamma rays
    telescopes
    cosmic ray
    cosmic rays
    Fermi Gamma-ray Space Telescope
    solar atmosphere
    heliosphere
    solar activity
    systematic errors
    rays
    cascades
    scattering
    electron
    radii
    atmosphere
    photons
    profiles
    prediction
    predictions

    Keywords

    • astroparticle physics
    • cosmic rays
    • gamma rays: general
    • Sun: atmosphere
    • Sun: heliosphere
    • Sun: X-rays, gamma rays

    ASJC Scopus subject areas

    • Space and Planetary Science
    • Astronomy and Astrophysics

    Cite this

    Abdo, A. A., Ackermann, M., Ajello, M., Baldini, L., Ballet, J., Barbiellini, G., ... Ziegler, M. (2011). Fermi large area telescope observations of two gamma-ray emission components from the quiescent sun. Astrophysical Journal, 734(2), [116]. https://doi.org/10.1088/0004-637X/734/2/116

    Fermi large area telescope observations of two gamma-ray emission components from the quiescent sun. / Abdo, A. A.; Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; De Angelis, A.; De Palma, F.; Dermer, C. D.; Digel, S. W.; Do Couto E Silva, E.; Drell, P. S.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Fortin, P.; Frailis, M.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grillo, L.; Guiriec, S.; Hadasch, D.; Hays, E.; Hughes, R. E.; Iafrate, G.; Jóhannesson, G.; Johnson, A. S.; Johnson, T. J.; Kamae, T.; Katagiri, H.; Kataoka, Jun; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S. H.; Lionetto, A. M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Pelassa, V.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Sadrozinski, H. F W; Schalk, T. L.; Sgrò, C.; Share, G. H.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Strong, A. W.; Takahashi, H.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vilchez, N.; Vitale, V.; Vladimirov, A. E.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ziegler, M.

    In: Astrophysical Journal, Vol. 734, No. 2, 116, 10.06.2011.

    Research output: Contribution to journalArticle

    Abdo, AA, Ackermann, M, Ajello, M, Baldini, L, Ballet, J, Barbiellini, G, Bastieri, D, Bechtol, K, Bellazzini, R, Berenji, B, Bonamente, E, Borgland, AW, Bouvier, A, Bregeon, J, Brez, A, Brigida, M, Bruel, P, Buehler, R, Buson, S, Caliandro, GA, Cameron, RA, Caraveo, PA, Casandjian, JM, Cecchi, C, Charles, E, Chekhtman, A, Chiang, J, Ciprini, S, Claus, R, Cohen-Tanugi, J, Conrad, J, Cutini, S, De Angelis, A, De Palma, F, Dermer, CD, Digel, SW, Do Couto E Silva, E, Drell, PS, Dubois, R, Favuzzi, C, Fegan, SJ, Focke, WB, Fortin, P, Frailis, M, Funk, S, Fusco, P, Gargano, F, Gasparrini, D, Gehrels, N, Germani, S, Giglietto, N, Giordano, F, Giroletti, M, Glanzman, T, Godfrey, G, Grenier, IA, Grillo, L, Guiriec, S, Hadasch, D, Hays, E, Hughes, RE, Iafrate, G, Jóhannesson, G, Johnson, AS, Johnson, TJ, Kamae, T, Katagiri, H, Kataoka, J, Knödlseder, J, Kuss, M, Lande, J, Latronico, L, Lee, SH, Lionetto, AM, Longo, F, Loparco, F, Lott, B, Lovellette, MN, Lubrano, P, Makeev, A, Mazziotta, MN, McEnery, JE, Mehault, J, Michelson, PF, Mitthumsiri, W, Mizuno, T, Moiseev, AA, Monte, C, Monzani, ME, Morselli, A, Moskalenko, IV, Murgia, S, Nakamori, T, Naumann-Godo, M, Nolan, PL, Norris, JP, Nuss, E, Ohsugi, T, Okumura, A, Omodei, N, Orlando, E, Ormes, JF, Ozaki, M, Paneque, D, Pelassa, V, Pesce-Rollins, M, Pierbattista, M, Piron, F, Porter, TA, Rainò, S, Rando, R, Razzano, M, Reimer, A, Reimer, O, Reposeur, T, Ritz, S, Sadrozinski, HFW, Schalk, TL, Sgrò, C, Share, GH, Siskind, EJ, Smith, PD, Spandre, G, Spinelli, P, Strickman, MS, Strong, AW, Takahashi, H, Tanaka, T, Thayer, JG, Thayer, JB, Thompson, DJ, Tibaldo, L, Torres, DF, Tosti, G, Tramacere, A, Troja, E, Uchiyama, Y, Usher, TL, Vandenbroucke, J, Vasileiou, V, Vianello, G, Vilchez, N, Vitale, V, Vladimirov, AE, Waite, AP, Wang, P, Winer, BL, Wood, KS, Yang, Z & Ziegler, M 2011, 'Fermi large area telescope observations of two gamma-ray emission components from the quiescent sun', Astrophysical Journal, vol. 734, no. 2, 116. https://doi.org/10.1088/0004-637X/734/2/116
    Abdo, A. A. ; Ackermann, M. ; Ajello, M. ; Baldini, L. ; Ballet, J. ; Barbiellini, G. ; Bastieri, D. ; Bechtol, K. ; Bellazzini, R. ; Berenji, B. ; Bonamente, E. ; Borgland, A. W. ; Bouvier, A. ; Bregeon, J. ; Brez, A. ; Brigida, M. ; Bruel, P. ; Buehler, R. ; Buson, S. ; Caliandro, G. A. ; Cameron, R. A. ; Caraveo, P. A. ; Casandjian, J. M. ; Cecchi, C. ; Charles, E. ; Chekhtman, A. ; Chiang, J. ; Ciprini, S. ; Claus, R. ; Cohen-Tanugi, J. ; Conrad, J. ; Cutini, S. ; De Angelis, A. ; De Palma, F. ; Dermer, C. D. ; Digel, S. W. ; Do Couto E Silva, E. ; Drell, P. S. ; Dubois, R. ; Favuzzi, C. ; Fegan, S. J. ; Focke, W. B. ; Fortin, P. ; Frailis, M. ; Funk, S. ; Fusco, P. ; Gargano, F. ; Gasparrini, D. ; Gehrels, N. ; Germani, S. ; Giglietto, N. ; Giordano, F. ; Giroletti, M. ; Glanzman, T. ; Godfrey, G. ; Grenier, I. A. ; Grillo, L. ; Guiriec, S. ; Hadasch, D. ; Hays, E. ; Hughes, R. E. ; Iafrate, G. ; Jóhannesson, G. ; Johnson, A. S. ; Johnson, T. J. ; Kamae, T. ; Katagiri, H. ; Kataoka, Jun ; Knödlseder, J. ; Kuss, M. ; Lande, J. ; Latronico, L. ; Lee, S. H. ; Lionetto, A. M. ; Longo, F. ; Loparco, F. ; Lott, B. ; Lovellette, M. N. ; Lubrano, P. ; Makeev, A. ; Mazziotta, M. N. ; McEnery, J. E. ; Mehault, J. ; Michelson, P. F. ; Mitthumsiri, W. ; Mizuno, T. ; Moiseev, A. A. ; Monte, C. ; Monzani, M. E. ; Morselli, A. ; Moskalenko, I. V. ; Murgia, S. ; Nakamori, T. ; Naumann-Godo, M. ; Nolan, P. L. ; Norris, J. P. ; Nuss, E. ; Ohsugi, T. ; Okumura, A. ; Omodei, N. ; Orlando, E. ; Ormes, J. F. ; Ozaki, M. ; Paneque, D. ; Pelassa, V. ; Pesce-Rollins, M. ; Pierbattista, M. ; Piron, F. ; Porter, T. A. ; Rainò, S. ; Rando, R. ; Razzano, M. ; Reimer, A. ; Reimer, O. ; Reposeur, T. ; Ritz, S. ; Sadrozinski, H. F W ; Schalk, T. L. ; Sgrò, C. ; Share, G. H. ; Siskind, E. J. ; Smith, P. D. ; Spandre, G. ; Spinelli, P. ; Strickman, M. S. ; Strong, A. W. ; Takahashi, H. ; Tanaka, T. ; Thayer, J. G. ; Thayer, J. B. ; Thompson, D. J. ; Tibaldo, L. ; Torres, D. F. ; Tosti, G. ; Tramacere, A. ; Troja, E. ; Uchiyama, Y. ; Usher, T. L. ; Vandenbroucke, J. ; Vasileiou, V. ; Vianello, G. ; Vilchez, N. ; Vitale, V. ; Vladimirov, A. E. ; Waite, A. P. ; Wang, P. ; Winer, B. L. ; Wood, K. S. ; Yang, Z. ; Ziegler, M. / Fermi large area telescope observations of two gamma-ray emission components from the quiescent sun. In: Astrophysical Journal. 2011 ; Vol. 734, No. 2.
    @article{25d1639f67f1401dbc198848173190d8,
    title = "Fermi large area telescope observations of two gamma-ray emission components from the quiescent sun",
    abstract = "We report the detection of high-energy γ-rays from the quiescent Sun with the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope (Fermi) during the first 18 months of the mission. These observations correspond to the recent period of low solar activity when the emission induced by cosmic rays (CRs) is brightest. For the first time, the high statistical significance of the observations allows clear separation of the two components: the point-like emission from the solar disk due to CR cascades in the solar atmosphere and extended emission from the inverse Compton (IC) scattering of CR electrons on solar photons in the heliosphere. The observed integral flux (≥100MeV) from the solar disk is (4.6 ± 0.2[statistical error] +1.0 - 0.8[systematic error]) × 10 -7cm-2s-1, which is 7 times higher than predicted by the {"}nominal{"} model of Seckel etal. In contrast, the observed integral flux (≥100MeV) of the extended emission from a region of 20° radius centered on the Sun, but excluding the disk itself, (6.8 ± 0.7[stat.]+0.5 - 0.4[syst.]) × 10 -7cm-2s-1, along with the observed spectrum and the angular profile, is in good agreement with the theoretical predictions for the IC emission.",
    keywords = "astroparticle physics, cosmic rays, gamma rays: general, Sun: atmosphere, Sun: heliosphere, Sun: X-rays, gamma rays",
    author = "Abdo, {A. A.} and M. Ackermann and M. Ajello and L. Baldini and J. Ballet and G. Barbiellini and D. Bastieri and K. Bechtol and R. Bellazzini and B. Berenji and E. Bonamente and Borgland, {A. W.} and A. Bouvier and J. Bregeon and A. Brez and M. Brigida and P. Bruel and R. Buehler and S. Buson and Caliandro, {G. A.} and Cameron, {R. A.} and Caraveo, {P. A.} and Casandjian, {J. M.} and C. Cecchi and E. Charles and A. Chekhtman and J. Chiang and S. Ciprini and R. Claus and J. Cohen-Tanugi and J. Conrad and S. Cutini and {De Angelis}, A. and {De Palma}, F. and Dermer, {C. D.} and Digel, {S. W.} and {Do Couto E Silva}, E. and Drell, {P. S.} and R. Dubois and C. Favuzzi and Fegan, {S. J.} and Focke, {W. B.} and P. Fortin and M. Frailis and S. Funk and P. Fusco and F. Gargano and D. Gasparrini and N. Gehrels and S. Germani and N. Giglietto and F. Giordano and M. Giroletti and T. Glanzman and G. Godfrey and Grenier, {I. A.} and L. Grillo and S. Guiriec and D. Hadasch and E. Hays and Hughes, {R. E.} and G. Iafrate and G. J{\'o}hannesson and Johnson, {A. S.} and Johnson, {T. J.} and T. Kamae and H. Katagiri and Jun Kataoka and J. Kn{\"o}dlseder and M. Kuss and J. Lande and L. Latronico and Lee, {S. H.} and Lionetto, {A. M.} and F. Longo and F. Loparco and B. Lott and Lovellette, {M. N.} and P. Lubrano and A. Makeev and Mazziotta, {M. N.} and McEnery, {J. E.} and J. Mehault and Michelson, {P. F.} and W. Mitthumsiri and T. Mizuno and Moiseev, {A. A.} and C. Monte and Monzani, {M. E.} and A. Morselli and Moskalenko, {I. V.} and S. Murgia and T. Nakamori and M. Naumann-Godo and Nolan, {P. L.} and Norris, {J. P.} and E. Nuss and T. Ohsugi and A. Okumura and N. Omodei and E. Orlando and Ormes, {J. F.} and M. Ozaki and D. Paneque and V. Pelassa and M. Pesce-Rollins and M. Pierbattista and F. Piron and Porter, {T. A.} and S. Rain{\`o} and R. Rando and M. Razzano and A. Reimer and O. Reimer and T. Reposeur and S. Ritz and Sadrozinski, {H. F W} and Schalk, {T. L.} and C. Sgr{\`o} and Share, {G. H.} and Siskind, {E. J.} and Smith, {P. D.} and G. Spandre and P. Spinelli and Strickman, {M. S.} and Strong, {A. W.} and H. Takahashi and T. Tanaka and Thayer, {J. G.} and Thayer, {J. B.} and Thompson, {D. J.} and L. Tibaldo and Torres, {D. F.} and G. Tosti and A. Tramacere and E. Troja and Y. Uchiyama and Usher, {T. L.} and J. Vandenbroucke and V. Vasileiou and G. Vianello and N. Vilchez and V. Vitale and Vladimirov, {A. E.} and Waite, {A. P.} and P. Wang and Winer, {B. L.} and Wood, {K. S.} and Z. Yang and M. Ziegler",
    year = "2011",
    month = "6",
    day = "10",
    doi = "10.1088/0004-637X/734/2/116",
    language = "English",
    volume = "734",
    journal = "Astrophysical Journal",
    issn = "0004-637X",
    publisher = "IOP Publishing Ltd.",
    number = "2",

    }

    TY - JOUR

    T1 - Fermi large area telescope observations of two gamma-ray emission components from the quiescent sun

    AU - Abdo, A. A.

    AU - Ackermann, M.

    AU - Ajello, M.

    AU - Baldini, L.

    AU - Ballet, J.

    AU - Barbiellini, G.

    AU - Bastieri, D.

    AU - Bechtol, K.

    AU - Bellazzini, R.

    AU - Berenji, B.

    AU - Bonamente, E.

    AU - Borgland, A. W.

    AU - Bouvier, A.

    AU - Bregeon, J.

    AU - Brez, A.

    AU - Brigida, M.

    AU - Bruel, P.

    AU - Buehler, R.

    AU - Buson, S.

    AU - Caliandro, G. A.

    AU - Cameron, R. A.

    AU - Caraveo, P. A.

    AU - Casandjian, J. M.

    AU - Cecchi, C.

    AU - Charles, E.

    AU - Chekhtman, A.

    AU - Chiang, J.

    AU - Ciprini, S.

    AU - Claus, R.

    AU - Cohen-Tanugi, J.

    AU - Conrad, J.

    AU - Cutini, S.

    AU - De Angelis, A.

    AU - De Palma, F.

    AU - Dermer, C. D.

    AU - Digel, S. W.

    AU - Do Couto E Silva, E.

    AU - Drell, P. S.

    AU - Dubois, R.

    AU - Favuzzi, C.

    AU - Fegan, S. J.

    AU - Focke, W. B.

    AU - Fortin, P.

    AU - Frailis, M.

    AU - Funk, S.

    AU - Fusco, P.

    AU - Gargano, F.

    AU - Gasparrini, D.

    AU - Gehrels, N.

    AU - Germani, S.

    AU - Giglietto, N.

    AU - Giordano, F.

    AU - Giroletti, M.

    AU - Glanzman, T.

    AU - Godfrey, G.

    AU - Grenier, I. A.

    AU - Grillo, L.

    AU - Guiriec, S.

    AU - Hadasch, D.

    AU - Hays, E.

    AU - Hughes, R. E.

    AU - Iafrate, G.

    AU - Jóhannesson, G.

    AU - Johnson, A. S.

    AU - Johnson, T. J.

    AU - Kamae, T.

    AU - Katagiri, H.

    AU - Kataoka, Jun

    AU - Knödlseder, J.

    AU - Kuss, M.

    AU - Lande, J.

    AU - Latronico, L.

    AU - Lee, S. H.

    AU - Lionetto, A. M.

    AU - Longo, F.

    AU - Loparco, F.

    AU - Lott, B.

    AU - Lovellette, M. N.

    AU - Lubrano, P.

    AU - Makeev, A.

    AU - Mazziotta, M. N.

    AU - McEnery, J. E.

    AU - Mehault, J.

    AU - Michelson, P. F.

    AU - Mitthumsiri, W.

    AU - Mizuno, T.

    AU - Moiseev, A. A.

    AU - Monte, C.

    AU - Monzani, M. E.

    AU - Morselli, A.

    AU - Moskalenko, I. V.

    AU - Murgia, S.

    AU - Nakamori, T.

    AU - Naumann-Godo, M.

    AU - Nolan, P. L.

    AU - Norris, J. P.

    AU - Nuss, E.

    AU - Ohsugi, T.

    AU - Okumura, A.

    AU - Omodei, N.

    AU - Orlando, E.

    AU - Ormes, J. F.

    AU - Ozaki, M.

    AU - Paneque, D.

    AU - Pelassa, V.

    AU - Pesce-Rollins, M.

    AU - Pierbattista, M.

    AU - Piron, F.

    AU - Porter, T. A.

    AU - Rainò, S.

    AU - Rando, R.

    AU - Razzano, M.

    AU - Reimer, A.

    AU - Reimer, O.

    AU - Reposeur, T.

    AU - Ritz, S.

    AU - Sadrozinski, H. F W

    AU - Schalk, T. L.

    AU - Sgrò, C.

    AU - Share, G. H.

    AU - Siskind, E. J.

    AU - Smith, P. D.

    AU - Spandre, G.

    AU - Spinelli, P.

    AU - Strickman, M. S.

    AU - Strong, A. W.

    AU - Takahashi, H.

    AU - Tanaka, T.

    AU - Thayer, J. G.

    AU - Thayer, J. B.

    AU - Thompson, D. J.

    AU - Tibaldo, L.

    AU - Torres, D. F.

    AU - Tosti, G.

    AU - Tramacere, A.

    AU - Troja, E.

    AU - Uchiyama, Y.

    AU - Usher, T. L.

    AU - Vandenbroucke, J.

    AU - Vasileiou, V.

    AU - Vianello, G.

    AU - Vilchez, N.

    AU - Vitale, V.

    AU - Vladimirov, A. E.

    AU - Waite, A. P.

    AU - Wang, P.

    AU - Winer, B. L.

    AU - Wood, K. S.

    AU - Yang, Z.

    AU - Ziegler, M.

    PY - 2011/6/10

    Y1 - 2011/6/10

    N2 - We report the detection of high-energy γ-rays from the quiescent Sun with the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope (Fermi) during the first 18 months of the mission. These observations correspond to the recent period of low solar activity when the emission induced by cosmic rays (CRs) is brightest. For the first time, the high statistical significance of the observations allows clear separation of the two components: the point-like emission from the solar disk due to CR cascades in the solar atmosphere and extended emission from the inverse Compton (IC) scattering of CR electrons on solar photons in the heliosphere. The observed integral flux (≥100MeV) from the solar disk is (4.6 ± 0.2[statistical error] +1.0 - 0.8[systematic error]) × 10 -7cm-2s-1, which is 7 times higher than predicted by the "nominal" model of Seckel etal. In contrast, the observed integral flux (≥100MeV) of the extended emission from a region of 20° radius centered on the Sun, but excluding the disk itself, (6.8 ± 0.7[stat.]+0.5 - 0.4[syst.]) × 10 -7cm-2s-1, along with the observed spectrum and the angular profile, is in good agreement with the theoretical predictions for the IC emission.

    AB - We report the detection of high-energy γ-rays from the quiescent Sun with the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope (Fermi) during the first 18 months of the mission. These observations correspond to the recent period of low solar activity when the emission induced by cosmic rays (CRs) is brightest. For the first time, the high statistical significance of the observations allows clear separation of the two components: the point-like emission from the solar disk due to CR cascades in the solar atmosphere and extended emission from the inverse Compton (IC) scattering of CR electrons on solar photons in the heliosphere. The observed integral flux (≥100MeV) from the solar disk is (4.6 ± 0.2[statistical error] +1.0 - 0.8[systematic error]) × 10 -7cm-2s-1, which is 7 times higher than predicted by the "nominal" model of Seckel etal. In contrast, the observed integral flux (≥100MeV) of the extended emission from a region of 20° radius centered on the Sun, but excluding the disk itself, (6.8 ± 0.7[stat.]+0.5 - 0.4[syst.]) × 10 -7cm-2s-1, along with the observed spectrum and the angular profile, is in good agreement with the theoretical predictions for the IC emission.

    KW - astroparticle physics

    KW - cosmic rays

    KW - gamma rays: general

    KW - Sun: atmosphere

    KW - Sun: heliosphere

    KW - Sun: X-rays, gamma rays

    UR - http://www.scopus.com/inward/record.url?scp=79958271049&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=79958271049&partnerID=8YFLogxK

    U2 - 10.1088/0004-637X/734/2/116

    DO - 10.1088/0004-637X/734/2/116

    M3 - Article

    VL - 734

    JO - Astrophysical Journal

    JF - Astrophysical Journal

    SN - 0004-637X

    IS - 2

    M1 - 116

    ER -