Ultra High Energy Cosmic Rays: The disappointing model Askhat Gazizov LNGS, INFN, Italy in collaboration with Roberto Aloisio and Veniamin Berezinsky April 06, 2011NPA5, Eilat, Israel Based on: Astroparticle Physics 34 (2011) 620–626 1

UHECR Spectrum April 06, 2011NPA5, Eilat, Israel dip/ankle steepening GZK-cutoff? Iron photo- disintegration? 2

GZK-cutoff in HiRes and PAO April 06, 2011NPA5, Eilat, Israel HiRes Auger But is it due to pion-photoproduction threshold ? 3

Unknowns in UHECR Physics April 06, 2011NPA5, Eilat, Israel UHECRs do exist with energies up to 3×10 20 eV. However … ??????  What is the chemical composition of CRs at these energies? protons heavy nuclei (Iron) 4 An important contribution from LHC at E c =14 TeV is expected.

Ankle Model April 06, 2011NPA5, Eilat, Israel Hillas, A. M., 1984, Ann. Rev. Astr. Astrophys. 22, 425; Bahcall, J. N., and E. Waxman, 2003, Phys. Lett. B556, 1. Problems: 1) acceleration in Galactic sources (SNe…) and 2) confinement in Galactic magnetic fields up to 10 EeV. 5

Pair-Production Dip Model April 06, 2011NPA5, Eilat, Israel If UHECRs are protons (HiRes): all features are well explained. dip GZK Modification factor Fe p V. Berezinsky, A.G., S. Grigorieva Phys. Rev. D74 (2006)

Mixed Composition Model April 06, 2011NPA5, Eilat, Israel Allard et al. (2005 – 2008) Combination of various nuclei adds to the observed UHECR spectrum. Protons dominate in the composition. GZK-cutoff is present. Correlation of CR arrival directions with positions of their sources in the sky, the common property of extragalactic protons, is expected. 7

(E) and RMS(X max ) (Hires) April 06, 2011NPA5, Eilat, Israel Both and RMS are consistent with protons. Combination of positions of the ‘dip’ and ‘GZK-cutoff’ features is in favor of protons. Data are consistent with dip/mixed composition models. No anisotropy in arrival directions was observed by HiRes ! 8

(E) and RMS(X max ) (Auger) April 06, 2011NPA5, Eilat, Israel (E) and RMS(X max ) indicate that chemical composition changes from protons to Iron with energy increasing. Nuclei. But an indication of anisotropy ( correlation with AGN? ) was observed. Is there difference between northern and southern skies? 9

April 06, 2011NPA5, Eilat, Israel We propose an answer: ‘The disappointing model’. R.Aloisio, V.Berezinsky, A.G., Astroparticle Physics 34 (2011) 620–626 10

Assumptions April 06, 2011 NPA5, Eilat, Israel and E 0 is universal, to be determined from data. 11

Eligible Source Parameters April 06, 2011NPA5, Eilat, Israel Calculate the extragalactic diffuse proton flux assuming power-law E 0 and normalize it (using A) by the Auger spectrum. Search for maximum E 0 allowable both by spectrum and mass composition. 12

Diffusive Propagation of Protons April 06, 2011NPA5, Eilat, Israel Maximum energy of protons E max ≈ 4 EeV.. Critical energy 13

Two-component Model April 06, 2011NPA5, Eilat, Israel Aloisio, Berezinsky, Grigorieva, arXiv: The steepening is due to Iron photodisintegration on CMBR. Include only protons and Iron. Spectrum is well explained, but the chemical composition in this model does not agree with the Auger data. An additional low-energy cutoff of the Iron spectrum is needed. 14

Diffusive Cutoff April 06, 2011NPA5, Eilat, Israel Chemical composition imposes hard generation function and strong magnetic field. 15

Position of Diffusive Cutoff April 06, 2011NPA5, Eilat, Israel16

Disappointing Consequences April 06, 2011NPA5, Eilat, Israel17

Thank you! April 06, 2011NPA5, Eilat, Israel18

April 06, 2011NPA5, Eilat, Israel19

Dip vs. Traditional Ankle April 06, 2011NPA5, Eilat, Israel Dip model Ankle model Maximum energy for shock acceleration 20

CR Spectrum April 06, 2011NPA5, Eilat, Israel21

Iron with E max = eV April 06, 2011NPA5, Eilat, Israel22

April 06, 2011NPA5, Eilat, Israel Spectrum with Iron and Ca 40 23

Auger Fluorescence Detector April 06, 2011NPA5, Eilat, Israel EAS Fluorescence light Mirror PMs 24