Fermi observations of γ-ray emission from the moon

A. A. Abdo, M. Ackermann, M. Ajello, W. B. Atwoo, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, K. Bechtol, R. Bellazzini, B. Berenji, R. D. Blandford, E. Bonamente, A. W. Borgland, E. Bottacini, A. Bouvier, J. Bregeon, M. Brigida, P. Bruel, R. BuehlerS. Buson, G. A. Caliandro, 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, F. D'Ammando, A. De Angelis, F. De Palma, C. D. Dermer, S. W. Digel, E. Do Couto E Silva, P. S. Drell, A. Drlica-Wagner, R. Dubois, C. Favuzzi, S. J. Fegan, W. B. Focke, P. Fortin, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, N. Gehrels, S. Germani, N. Giglietto, P. Giommi, F. Giordano, M. Giroletti, T. Glanzman, G. Godfrey, G. A. Gomez-Vargas, I. A. Grenier, J. E. Grove, S. Guiriec, D. Hadasch, E. Hays, A. B. Hill, D. Horan, X. Hou, R. E. Hughes, G. Iafrate, M. S. Jackson, G. Jóhannesson, A. S. Johnson, T. Kamae, H. Katagiri, Jun Kataoka, J. Knödlseder, M. Kuss, J. Lande, S. Larsson, L. Latronico, M. Lemoine-Goumard, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, 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, M. Naumann-Godo, P. L. Nolan, J. P. Norris, E. Nuss, M. Ohno, T. Ohsugi, A. Okumura, N. Omodei, M. Orienti, E. Orlando, J. F. Ormes, M. Ozaki, D. Paneque, J. H. Panetta, D. Parent, M. Pesce-Rollins, M. Pierbattista, F. Piron, G. Pivato, H. Poon, T. A. Porter, D. Prokhorov, S. Rainò, R. Rando, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, T. Reposeur, L. S. Rochester, M. Roth, H. F W Sadrozinski, D. A. Sanchez, C. Sbarra, T. L. Schalk, C. Sgrò, G. H. Share, E. J. Siskind, G. Spandre, P. Spinelli, Stawarz, H. Takahashi, T. Tanaka, J. G. Thayer, J. B. Thayer, D. J. Thompson, L. Tibaldo, M. Tinivella, D. F. Torres, G. Tosti, E. Troja, Y. Uchiyama, T. L. Usher, J. Vandenbroucke, V. Vasileiou, G. Vianello, V. Vitale, A. P. Waite, P. Wang, B. L. Winer, D. L. Wood, K. S. Wood, Z. Yang, S. Zimmer

    Research output: Contribution to journalArticle

    18 Citations (Scopus)

    Abstract

    We report on the detection of high-energy γ-ray emission from the Moon during the first 24 months of observations by the Fermi Large Area Telescope (LAT). This emission comes from particle cascades produced by cosmic-ray (CR) nuclei and electrons interacting with the lunar surface. The differential spectrum of the Moon is soft and can be described as a log-parabolic function with an effective cutoff at 2-3GeV, while the average integral flux measured with the LAT from the beginning of observations in 2008 August to the end of 2010 August is F(>cm-2s-1. This flux is about a factor 2-3 higher than that observed between 1991 and 1994 by the EGRET experiment on board the Compton Gamma Ray Observatory, F(>100 MeV) ≈ 5 × 10-7cm-2s-1, when solar activity was relatively high. The higher γ-ray flux measured by Fermi is consistent with the deep solar minimum conditions during the first 24 months of the mission, which reduced effects of heliospheric modulation, and thus increased the heliospheric flux of Galactic CRs. A detailed comparison of the light curve with McMurdo Neutron Monitor rates suggests a correlation of the trends. The Moon and the Sun are so far the only known bright emitters of γ-rays with fast celestial motion. Their paths across the sky are projected onto the Galactic center and high Galactic latitudes as well as onto other areas crowded with high-energy γ-ray sources. Analysis of the lunar and solar emission may thus be important for studies of weak and transient sources near the ecliptic.

    Original languageEnglish
    Article number140
    JournalAstrophysical Journal
    Volume758
    Issue number2
    DOIs
    Publication statusPublished - 2012 Oct 20

    Fingerprint

    natural satellites
    Moon
    rays
    moon
    telescopes
    Gamma Ray Observatory
    solar activity
    cosmic ray
    ecliptic
    lunar surface
    energy
    observatory
    light curve
    sky
    monitors
    cosmic rays
    electron
    cascades
    emitters
    sun

    Keywords

    • astroparticle physics
    • gamma rays: general
    • Moon

    ASJC Scopus subject areas

    • Space and Planetary Science
    • Astronomy and Astrophysics

    Cite this

    Abdo, A. A., Ackermann, M., Ajello, M., Atwoo, W. B., Baldini, L., Ballet, J., ... Zimmer, S. (2012). Fermi observations of γ-ray emission from the moon. Astrophysical Journal, 758(2), [140]. https://doi.org/10.1088/0004-637X/758/2/140

    Fermi observations of γ-ray emission from the moon. / Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwoo, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bonamente, E.; Borgland, A. W.; Bottacini, E.; Bouvier, A.; Bregeon, J.; 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.; D'Ammando, F.; De Angelis, A.; De Palma, F.; Dermer, C. D.; Digel, S. W.; Do Couto E Silva, E.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Fortin, P.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gehrels, N.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hays, E.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Iafrate, G.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Katagiri, H.; Kataoka, Jun; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; 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.; Naumann-Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Poon, H.; Porter, T. A.; Prokhorov, D.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Rochester, L. S.; Roth, M.; Sadrozinski, H. F W; Sanchez, D. A.; Sbarra, C.; Schalk, T. L.; Sgrò, C.; Share, G. H.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Stawarz; Takahashi, H.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, D. L.; Wood, K. S.; Yang, Z.; Zimmer, S.

    In: Astrophysical Journal, Vol. 758, No. 2, 140, 20.10.2012.

    Research output: Contribution to journalArticle

    Abdo, AA, Ackermann, M, Ajello, M, Atwoo, WB, Baldini, L, Ballet, J, Barbiellini, G, Bastieri, D, Bechtol, K, Bellazzini, R, Berenji, B, Blandford, RD, Bonamente, E, Borgland, AW, Bottacini, E, Bouvier, A, Bregeon, J, 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, D'Ammando, F, De Angelis, A, De Palma, F, Dermer, CD, Digel, SW, Do Couto E Silva, E, Drell, PS, Drlica-Wagner, A, Dubois, R, Favuzzi, C, Fegan, SJ, Focke, WB, Fortin, P, Fukazawa, Y, Funk, S, Fusco, P, Gargano, F, Gehrels, N, Germani, S, Giglietto, N, Giommi, P, Giordano, F, Giroletti, M, Glanzman, T, Godfrey, G, Gomez-Vargas, GA, Grenier, IA, Grove, JE, Guiriec, S, Hadasch, D, Hays, E, Hill, AB, Horan, D, Hou, X, Hughes, RE, Iafrate, G, Jackson, MS, Jóhannesson, G, Johnson, AS, Kamae, T, Katagiri, H, Kataoka, J, Knödlseder, J, Kuss, M, Lande, J, Larsson, S, Latronico, L, Lemoine-Goumard, M, Longo, F, Loparco, F, Lott, B, Lovellette, MN, Lubrano, P, Mazziotta, MN, McEnery, JE, Mehault, J, Michelson, PF, Mitthumsiri, W, Mizuno, T, Moiseev, AA, Monte, C, Monzani, ME, Morselli, A, Moskalenko, IV, Murgia, S, Naumann-Godo, M, Nolan, PL, Norris, JP, Nuss, E, Ohno, M, Ohsugi, T, Okumura, A, Omodei, N, Orienti, M, Orlando, E, Ormes, JF, Ozaki, M, Paneque, D, Panetta, JH, Parent, D, Pesce-Rollins, M, Pierbattista, M, Piron, F, Pivato, G, Poon, H, Porter, TA, Prokhorov, D, Rainò, S, Rando, R, Razzano, M, Razzaque, S, Reimer, A, Reimer, O, Reposeur, T, Rochester, LS, Roth, M, Sadrozinski, HFW, Sanchez, DA, Sbarra, C, Schalk, TL, Sgrò, C, Share, GH, Siskind, EJ, Spandre, G, Spinelli, P, Stawarz, Takahashi, H, Tanaka, T, Thayer, JG, Thayer, JB, Thompson, DJ, Tibaldo, L, Tinivella, M, Torres, DF, Tosti, G, Troja, E, Uchiyama, Y, Usher, TL, Vandenbroucke, J, Vasileiou, V, Vianello, G, Vitale, V, Waite, AP, Wang, P, Winer, BL, Wood, DL, Wood, KS, Yang, Z & Zimmer, S 2012, 'Fermi observations of γ-ray emission from the moon', Astrophysical Journal, vol. 758, no. 2, 140. https://doi.org/10.1088/0004-637X/758/2/140
    Abdo AA, Ackermann M, Ajello M, Atwoo WB, Baldini L, Ballet J et al. Fermi observations of γ-ray emission from the moon. Astrophysical Journal. 2012 Oct 20;758(2). 140. https://doi.org/10.1088/0004-637X/758/2/140
    Abdo, A. A. ; Ackermann, M. ; Ajello, M. ; Atwoo, W. B. ; Baldini, L. ; Ballet, J. ; Barbiellini, G. ; Bastieri, D. ; Bechtol, K. ; Bellazzini, R. ; Berenji, B. ; Blandford, R. D. ; Bonamente, E. ; Borgland, A. W. ; Bottacini, E. ; Bouvier, A. ; Bregeon, J. ; 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. ; D'Ammando, F. ; De Angelis, A. ; De Palma, F. ; Dermer, C. D. ; Digel, S. W. ; Do Couto E Silva, E. ; Drell, P. S. ; Drlica-Wagner, A. ; Dubois, R. ; Favuzzi, C. ; Fegan, S. J. ; Focke, W. B. ; Fortin, P. ; Fukazawa, Y. ; Funk, S. ; Fusco, P. ; Gargano, F. ; Gehrels, N. ; Germani, S. ; Giglietto, N. ; Giommi, P. ; Giordano, F. ; Giroletti, M. ; Glanzman, T. ; Godfrey, G. ; Gomez-Vargas, G. A. ; Grenier, I. A. ; Grove, J. E. ; Guiriec, S. ; Hadasch, D. ; Hays, E. ; Hill, A. B. ; Horan, D. ; Hou, X. ; Hughes, R. E. ; Iafrate, G. ; Jackson, M. S. ; Jóhannesson, G. ; Johnson, A. S. ; Kamae, T. ; Katagiri, H. ; Kataoka, Jun ; Knödlseder, J. ; Kuss, M. ; Lande, J. ; Larsson, S. ; Latronico, L. ; Lemoine-Goumard, M. ; Longo, F. ; Loparco, F. ; Lott, B. ; Lovellette, M. N. ; Lubrano, P. ; 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. ; Naumann-Godo, M. ; Nolan, P. L. ; Norris, J. P. ; Nuss, E. ; Ohno, M. ; Ohsugi, T. ; Okumura, A. ; Omodei, N. ; Orienti, M. ; Orlando, E. ; Ormes, J. F. ; Ozaki, M. ; Paneque, D. ; Panetta, J. H. ; Parent, D. ; Pesce-Rollins, M. ; Pierbattista, M. ; Piron, F. ; Pivato, G. ; Poon, H. ; Porter, T. A. ; Prokhorov, D. ; Rainò, S. ; Rando, R. ; Razzano, M. ; Razzaque, S. ; Reimer, A. ; Reimer, O. ; Reposeur, T. ; Rochester, L. S. ; Roth, M. ; Sadrozinski, H. F W ; Sanchez, D. A. ; Sbarra, C. ; Schalk, T. L. ; Sgrò, C. ; Share, G. H. ; Siskind, E. J. ; Spandre, G. ; Spinelli, P. ; Stawarz ; Takahashi, H. ; Tanaka, T. ; Thayer, J. G. ; Thayer, J. B. ; Thompson, D. J. ; Tibaldo, L. ; Tinivella, M. ; Torres, D. F. ; Tosti, G. ; Troja, E. ; Uchiyama, Y. ; Usher, T. L. ; Vandenbroucke, J. ; Vasileiou, V. ; Vianello, G. ; Vitale, V. ; Waite, A. P. ; Wang, P. ; Winer, B. L. ; Wood, D. L. ; Wood, K. S. ; Yang, Z. ; Zimmer, S. / Fermi observations of γ-ray emission from the moon. In: Astrophysical Journal. 2012 ; Vol. 758, No. 2.
    @article{ec446e1bad9845e1b8a3842202b367b3,
    title = "Fermi observations of γ-ray emission from the moon",
    abstract = "We report on the detection of high-energy γ-ray emission from the Moon during the first 24 months of observations by the Fermi Large Area Telescope (LAT). This emission comes from particle cascades produced by cosmic-ray (CR) nuclei and electrons interacting with the lunar surface. The differential spectrum of the Moon is soft and can be described as a log-parabolic function with an effective cutoff at 2-3GeV, while the average integral flux measured with the LAT from the beginning of observations in 2008 August to the end of 2010 August is F(>cm-2s-1. This flux is about a factor 2-3 higher than that observed between 1991 and 1994 by the EGRET experiment on board the Compton Gamma Ray Observatory, F(>100 MeV) ≈ 5 × 10-7cm-2s-1, when solar activity was relatively high. The higher γ-ray flux measured by Fermi is consistent with the deep solar minimum conditions during the first 24 months of the mission, which reduced effects of heliospheric modulation, and thus increased the heliospheric flux of Galactic CRs. A detailed comparison of the light curve with McMurdo Neutron Monitor rates suggests a correlation of the trends. The Moon and the Sun are so far the only known bright emitters of γ-rays with fast celestial motion. Their paths across the sky are projected onto the Galactic center and high Galactic latitudes as well as onto other areas crowded with high-energy γ-ray sources. Analysis of the lunar and solar emission may thus be important for studies of weak and transient sources near the ecliptic.",
    keywords = "astroparticle physics, gamma rays: general, Moon",
    author = "Abdo, {A. A.} and M. Ackermann and M. Ajello and Atwoo, {W. B.} and L. Baldini and J. Ballet and G. Barbiellini and D. Bastieri and K. Bechtol and R. Bellazzini and B. Berenji and Blandford, {R. D.} and E. Bonamente and Borgland, {A. W.} and E. Bottacini and A. Bouvier and J. Bregeon 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 F. D'Ammando 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 A. Drlica-Wagner and R. Dubois and C. Favuzzi and Fegan, {S. J.} and Focke, {W. B.} and P. Fortin and Y. Fukazawa and S. Funk and P. Fusco and F. Gargano and N. Gehrels and S. Germani and N. Giglietto and P. Giommi and F. Giordano and M. Giroletti and T. Glanzman and G. Godfrey and Gomez-Vargas, {G. A.} and Grenier, {I. A.} and Grove, {J. E.} and S. Guiriec and D. Hadasch and E. Hays and Hill, {A. B.} and D. Horan and X. Hou and Hughes, {R. E.} and G. Iafrate and Jackson, {M. S.} and G. J{\'o}hannesson and Johnson, {A. S.} and T. Kamae and H. Katagiri and Jun Kataoka and J. Kn{\"o}dlseder and M. Kuss and J. Lande and S. Larsson and L. Latronico and M. Lemoine-Goumard and F. Longo and F. Loparco and B. Lott and Lovellette, {M. N.} and P. Lubrano 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 M. Naumann-Godo and Nolan, {P. L.} and Norris, {J. P.} and E. Nuss and M. Ohno and T. Ohsugi and A. Okumura and N. Omodei and M. Orienti and E. Orlando and Ormes, {J. F.} and M. Ozaki and D. Paneque and Panetta, {J. H.} and D. Parent and M. Pesce-Rollins and M. Pierbattista and F. Piron and G. Pivato and H. Poon and Porter, {T. A.} and D. Prokhorov and S. Rain{\`o} and R. Rando and M. Razzano and S. Razzaque and A. Reimer and O. Reimer and T. Reposeur and Rochester, {L. S.} and M. Roth and Sadrozinski, {H. F W} and Sanchez, {D. A.} and C. Sbarra and Schalk, {T. L.} and C. Sgr{\`o} and Share, {G. H.} and Siskind, {E. J.} and G. Spandre and P. Spinelli and Stawarz and H. Takahashi and T. Tanaka and Thayer, {J. G.} and Thayer, {J. B.} and Thompson, {D. J.} and L. Tibaldo and M. Tinivella and Torres, {D. F.} and G. Tosti and E. Troja and Y. Uchiyama and Usher, {T. L.} and J. Vandenbroucke and V. Vasileiou and G. Vianello and V. Vitale and Waite, {A. P.} and P. Wang and Winer, {B. L.} and Wood, {D. L.} and Wood, {K. S.} and Z. Yang and S. Zimmer",
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    month = "10",
    day = "20",
    doi = "10.1088/0004-637X/758/2/140",
    language = "English",
    volume = "758",
    journal = "Astrophysical Journal",
    issn = "0004-637X",
    publisher = "IOP Publishing Ltd.",
    number = "2",

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    TY - JOUR

    T1 - Fermi observations of γ-ray emission from the moon

    AU - Abdo, A. A.

    AU - Ackermann, M.

    AU - Ajello, M.

    AU - Atwoo, W. B.

    AU - Baldini, L.

    AU - Ballet, J.

    AU - Barbiellini, G.

    AU - Bastieri, D.

    AU - Bechtol, K.

    AU - Bellazzini, R.

    AU - Berenji, B.

    AU - Blandford, R. D.

    AU - Bonamente, E.

    AU - Borgland, A. W.

    AU - Bottacini, E.

    AU - Bouvier, A.

    AU - Bregeon, J.

    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 - D'Ammando, F.

    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 - Drlica-Wagner, A.

    AU - Dubois, R.

    AU - Favuzzi, C.

    AU - Fegan, S. J.

    AU - Focke, W. B.

    AU - Fortin, P.

    AU - Fukazawa, Y.

    AU - Funk, S.

    AU - Fusco, P.

    AU - Gargano, F.

    AU - Gehrels, N.

    AU - Germani, S.

    AU - Giglietto, N.

    AU - Giommi, P.

    AU - Giordano, F.

    AU - Giroletti, M.

    AU - Glanzman, T.

    AU - Godfrey, G.

    AU - Gomez-Vargas, G. A.

    AU - Grenier, I. A.

    AU - Grove, J. E.

    AU - Guiriec, S.

    AU - Hadasch, D.

    AU - Hays, E.

    AU - Hill, A. B.

    AU - Horan, D.

    AU - Hou, X.

    AU - Hughes, R. E.

    AU - Iafrate, G.

    AU - Jackson, M. S.

    AU - Jóhannesson, G.

    AU - Johnson, A. S.

    AU - Kamae, T.

    AU - Katagiri, H.

    AU - Kataoka, Jun

    AU - Knödlseder, J.

    AU - Kuss, M.

    AU - Lande, J.

    AU - Larsson, S.

    AU - Latronico, L.

    AU - Lemoine-Goumard, M.

    AU - Longo, F.

    AU - Loparco, F.

    AU - Lott, B.

    AU - Lovellette, M. N.

    AU - Lubrano, P.

    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 - Naumann-Godo, M.

    AU - Nolan, P. L.

    AU - Norris, J. P.

    AU - Nuss, E.

    AU - Ohno, M.

    AU - Ohsugi, T.

    AU - Okumura, A.

    AU - Omodei, N.

    AU - Orienti, M.

    AU - Orlando, E.

    AU - Ormes, J. F.

    AU - Ozaki, M.

    AU - Paneque, D.

    AU - Panetta, J. H.

    AU - Parent, D.

    AU - Pesce-Rollins, M.

    AU - Pierbattista, M.

    AU - Piron, F.

    AU - Pivato, G.

    AU - Poon, H.

    AU - Porter, T. A.

    AU - Prokhorov, D.

    AU - Rainò, S.

    AU - Rando, R.

    AU - Razzano, M.

    AU - Razzaque, S.

    AU - Reimer, A.

    AU - Reimer, O.

    AU - Reposeur, T.

    AU - Rochester, L. S.

    AU - Roth, M.

    AU - Sadrozinski, H. F W

    AU - Sanchez, D. A.

    AU - Sbarra, C.

    AU - Schalk, T. L.

    AU - Sgrò, C.

    AU - Share, G. H.

    AU - Siskind, E. J.

    AU - Spandre, G.

    AU - Spinelli, P.

    AU - Stawarz,

    AU - Takahashi, H.

    AU - Tanaka, T.

    AU - Thayer, J. G.

    AU - Thayer, J. B.

    AU - Thompson, D. J.

    AU - Tibaldo, L.

    AU - Tinivella, M.

    AU - Torres, D. F.

    AU - Tosti, G.

    AU - Troja, E.

    AU - Uchiyama, Y.

    AU - Usher, T. L.

    AU - Vandenbroucke, J.

    AU - Vasileiou, V.

    AU - Vianello, G.

    AU - Vitale, V.

    AU - Waite, A. P.

    AU - Wang, P.

    AU - Winer, B. L.

    AU - Wood, D. L.

    AU - Wood, K. S.

    AU - Yang, Z.

    AU - Zimmer, S.

    PY - 2012/10/20

    Y1 - 2012/10/20

    N2 - We report on the detection of high-energy γ-ray emission from the Moon during the first 24 months of observations by the Fermi Large Area Telescope (LAT). This emission comes from particle cascades produced by cosmic-ray (CR) nuclei and electrons interacting with the lunar surface. The differential spectrum of the Moon is soft and can be described as a log-parabolic function with an effective cutoff at 2-3GeV, while the average integral flux measured with the LAT from the beginning of observations in 2008 August to the end of 2010 August is F(>cm-2s-1. This flux is about a factor 2-3 higher than that observed between 1991 and 1994 by the EGRET experiment on board the Compton Gamma Ray Observatory, F(>100 MeV) ≈ 5 × 10-7cm-2s-1, when solar activity was relatively high. The higher γ-ray flux measured by Fermi is consistent with the deep solar minimum conditions during the first 24 months of the mission, which reduced effects of heliospheric modulation, and thus increased the heliospheric flux of Galactic CRs. A detailed comparison of the light curve with McMurdo Neutron Monitor rates suggests a correlation of the trends. The Moon and the Sun are so far the only known bright emitters of γ-rays with fast celestial motion. Their paths across the sky are projected onto the Galactic center and high Galactic latitudes as well as onto other areas crowded with high-energy γ-ray sources. Analysis of the lunar and solar emission may thus be important for studies of weak and transient sources near the ecliptic.

    AB - We report on the detection of high-energy γ-ray emission from the Moon during the first 24 months of observations by the Fermi Large Area Telescope (LAT). This emission comes from particle cascades produced by cosmic-ray (CR) nuclei and electrons interacting with the lunar surface. The differential spectrum of the Moon is soft and can be described as a log-parabolic function with an effective cutoff at 2-3GeV, while the average integral flux measured with the LAT from the beginning of observations in 2008 August to the end of 2010 August is F(>cm-2s-1. This flux is about a factor 2-3 higher than that observed between 1991 and 1994 by the EGRET experiment on board the Compton Gamma Ray Observatory, F(>100 MeV) ≈ 5 × 10-7cm-2s-1, when solar activity was relatively high. The higher γ-ray flux measured by Fermi is consistent with the deep solar minimum conditions during the first 24 months of the mission, which reduced effects of heliospheric modulation, and thus increased the heliospheric flux of Galactic CRs. A detailed comparison of the light curve with McMurdo Neutron Monitor rates suggests a correlation of the trends. The Moon and the Sun are so far the only known bright emitters of γ-rays with fast celestial motion. Their paths across the sky are projected onto the Galactic center and high Galactic latitudes as well as onto other areas crowded with high-energy γ-ray sources. Analysis of the lunar and solar emission may thus be important for studies of weak and transient sources near the ecliptic.

    KW - astroparticle physics

    KW - gamma rays: general

    KW - Moon

    UR - http://www.scopus.com/inward/record.url?scp=84867385972&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=84867385972&partnerID=8YFLogxK

    U2 - 10.1088/0004-637X/758/2/140

    DO - 10.1088/0004-637X/758/2/140

    M3 - Article

    AN - SCOPUS:84867385972

    VL - 758

    JO - Astrophysical Journal

    JF - Astrophysical Journal

    SN - 0004-637X

    IS - 2

    M1 - 140

    ER -