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. CaliandroR. 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, J. 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

66 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

Keywords

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

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

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., ... 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