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High Energy Cosmic Rays Eli Waxman Weizmann Institute, ISRAEL
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Cosmic ray flux and Composition E [GeV] log [dJ/dE] 110 610 E -2.7 E -3 Heavy Nuclei Protons U cr (1GeV)=1 eV/cm 3 Galactic plane enhancement Isotropy Galactic X-Galactic (?) [Blandford & Eichler, Phys. Rep. 87; Axford, ApJS 94; Bird et al. 94; Nagano & Watson, Rev. Mod. Phys. 00; Abu-Zayyad et al. 01] Lighter
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Composition HiRes/MIAFly’s Eye [Abu-Zayyad et al. 01] [Bird et al. 94]
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Acceleration Problem [K. Arisaka 02]
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X-Galactic Ultra High Energy p High energy, XG sources exist p (pN) ’ s e ’ s, ’ s UHE p flux Handle on flux, detector size Prime telescope motivation: Identify UHE p source(s)
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The Data
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Data- Calibrated at 10 19 eV
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Model Fly ’ s Eye fit for Galactic heavy (<10 19 eV): J G ~E -3.50 X-Galactic protons: Generation spectrum (shock acceleration): Generation rate (GRB motivated): Redshift evolution ~ SFR (GRB motivated). [EW 95]
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Model vs. Data X-G Model: [Bahcall & EW 02] Ruled out 7
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Data/Model consistency Define: 10 19 eV to 10 20 eV: Data (YK,AG,FE,HR) and model consistent with XG protons, + GZK
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Conclusions are Robust
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A note on GRBs Energy generation rate: Proton acceleration: E p,max ~ 10 21 eV Claims for E p,max << 10 21 eV - irrelevant for the model (May be valid for “ external shocks ” only) For more: See talk by P. Meszaros and Lec. Notes Phys. review (astro-ph/0103186) [Frail et al. 01; Schmidt 01]
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Summary Yakutsk, Fly ’ s Eye, HiRes: Consistent with XG protons: + GZK (Robust; Consistent with GRB model predictions [see talk by P. Meszaros] ) AGASA (25% of total exposure): Consistent below 10 20 eV Excess above 10 20 eV: 2.2+/-0.8 8 observed New source/ New physics/ 25% energy Local inhomogeneity over-estimate Need: Hybrid 10 18 eV to 10 20 eV observations ??
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Implications for telescopes X-Galactic sources of high energy ’ s are out there UHE p flux constrains expected flux ~ 1 km 3 scale required at 1 to 10 3 TeV energies >> 1 km 3 required at >>10 3 TeV ( see J. Bahcall ’ s talk )
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