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 gamma-ray emission from Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range similar to 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 similar to 200 GeV, respectively.

Ackermann M, Ajello M, Albert A, Allafort A, Baldini L, Barbiellini G, et al. (2014). Inferred Cosmic-Ray Spectrum from Fermi Large Area Telescope gamma-Ray Observations of Earth's Limb. PHYSICAL REVIEW LETTERS, 112(15), 1-7 [10.1103/PhysRevLett.112.151103].

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

D'AMMANDO, FILIPPO;
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 gamma-ray emission from Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range similar to 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 similar to 200 GeV, respectively.
2014
Ackermann M, Ajello M, Albert A, Allafort A, Baldini L, Barbiellini G, et al. (2014). Inferred Cosmic-Ray Spectrum from Fermi Large Area Telescope gamma-Ray Observations of Earth's Limb. PHYSICAL REVIEW LETTERS, 112(15), 1-7 [10.1103/PhysRevLett.112.151103].
Ackermann M; Ajello M; Albert A; Allafort A; Baldini L; Barbiellini G; Bastieri D; Bechtol K; Bellazzini R; Blandford RD; Bloom ED; Bonamente E; Botta...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/595759
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