Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the γ-ray emission from Earth’s limb for an indirect measurement of the local spectrum of CR protons in the energy range ∼90  GeV–6  TeV (derived from a photon energy range 15 GeV–1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68±0.04 and 2.61±0.08 above ∼200  GeV, respectively.

Inferred Cosmic-Ray Spectrum from Fermi Large Area Telescope Gamma-Ray Observations of Earth's Limb

BALDINI, LUCA;RAZZANO, MASSIMILIANO;TINIVELLA, MARCO;
2014

Abstract

Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the γ-ray emission from Earth’s limb for an indirect measurement of the local spectrum of CR protons in the energy range ∼90  GeV–6  TeV (derived from a photon energy range 15 GeV–1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68±0.04 and 2.61±0.08 above ∼200  GeV, respectively.
M., Ackermann; M., Ajello; A., Albert; A., Allafort; Baldini, Luca; G., Barbiellini; D., Bastieri; K., Bechtol; R., Bellazzini; Blandford, R. ?. D.; Bloom, E. ?. D.; E., Bonamente; E., Bottacini; A., Bouvier; Brandt, T. ?. J.; M., Brigida; P., Bruel; R., Buehler; S., Buson; Caliandro, G. ?. A.; Cameron, R. ?. A.; Caraveo, P. ?. A.; C., Cecchi; E., Charles; Chaves, R. ?. C. ?. G.; A., Chekhtman; J., Chiang; G., Chiaro; S., Ciprini; R., Claus; J., Cohen Tanugi; J., Conrad; S., Cutini; M., Dalton; F., D?ammando; A., de Angelis; F., de Palma; Dermer, C. ?. D.; Digel, S. ?. W.; L., Di Venere; E. do Couto e., Silva; Drell, P. ?. S.; A., Drlica Wagner; C., Favuzzi; Fegan, S. ?. J.; Ferrara, E. ?. C.; Focke, W. ?. B.; A., Franckowiak; Y., Fukazawa; S., Funk; P., Fusco; F., Gargano; D., Gasparrini; S., Germani; N., Giglietto; F., Giordano; M., Giroletti; T., Glanzman; G., Godfrey; Gomez Vargas, G. ?. A.; Grenier, I. ?. A.; Grove, J. ?. E.; S., Guiriec; M., Gustafsson; D., Hadasch; Y., Hanabata; Harding, A. ?. K.; M., Hayashida; K., Hayashi; Hewitt, J. ?. W.; D., Horan; X., Hou; Hughes, R. ?. E.; Y., Inoue; Jackson, M. ?. S.; T., Jogler; G., J?hannesson; Johnson, A. ?. S.; T., Kamae; T., Kawano; J., Kn?dlseder; M., Kuss; J., Lande; S., Larsson; L., Latronico; F., Longo; F., Loparco; Lovellette, M. ?. N.; P., Lubrano; M., Mayer; Mazziotta, M. ?. N.; Mcenery, J. ?. E.; J., Mehault; Michelson, P. ?. F.; W., Mitthumsiri; T., Mizuno; Moiseev, A. ?. A.; C., Monte; Monzani, M. ?. E.; A., Morselli; Moskalenko, I. ?. V.; S., Murgia; R., Nemmen; E., Nuss; T., Ohsugi; A., Okumura; M., Orienti; E., Orlando; Ormes, J. ?. F.; D., Paneque; Panetta, J. ?. H.; Perkins, J. ?. S.; M., Pesce Rollins; F., Piron; G., Pivato; Porter, T. ?. A.; S., Rain?; R., Rando; Razzano, Massimiliano; S., Razzaque; A., Reimer; O., Reimer; S., Ritz; M., Roth; M., Schaal; A., Schulz; C., Sgr?; Siskind, E. ?. J.; G., Spandre; P., Spinelli; Strong, A. ?. W.; H., Takahashi; Y., Takeuchi; Thayer, J. ?. G.; Thayer, J. ?. B.; Thompson, D. ?. J.; L., Tibaldo; Tinivella, Marco; Torres, D. ?. F.; G., Tosti; E., Troja; V., Tronconi; Usher, T. ?. L.; J., Vandenbroucke; V., Vasileiou; G., Vianello; V., Vitale; M., Werner; Winer, B. ?. L.; Wood, K. ?. S.; M., Wood; Z., Yang
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/504467
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