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UHECR photons

UHECR photons. Dmitry Semikoz APC (Paris). G.Gelmini (UCLA), O.Kalashev (INR, Moscow) and I.Tkachev (CERN), 2005. INTRODUCTION. AUGER experiment combining ground array with fluorescence such will resolve most of this issues in 1-2 years from now.

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UHECR photons

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  1. UHECR photons Dmitry Semikoz APC (Paris) G.Gelmini (UCLA), O.Kalashev (INR, Moscow) and I.Tkachev (CERN), 2005

  2. INTRODUCTION

  3. AUGER experiment combining ground array with fluorescence such will resolve most of this issues in 1-2 years from now.

  4. Statistics is not a problem anymore! Expect: ~445000 events/year 1017 - 1018 eV ~125000 events/year 1018 - 1919 eV ~5000 events/year > 1019 eV ~ 350 events/year > 4 x 1019 eV 10% of these are hybrid (scaling from present yields) compare to AGASA: 72 events with E> 4 x 1019 eVin 10 years

  5. Propagation of protons and photons

  6. pair production energy loss -resonance pion production energy loss multi-pion production pion production rate The Greisen-Zatsepin-Kuzmin (GZK) effect Nucleons can produce pions on the cosmic microwave background  nucleon • sources must be in cosmological backyard within 50-100 Mpc from Earth (compare to the Universe size ~ 5000 Mpc)

  7. Proton deflections in extragalactic magnetic field within 105 Mpc from our Galaxy Extragalactic magnetic field in R=50 Mpc large scale structure box Dolag et al, 2003 Sigl et al, 2002-2003

  8. Galactic Magnetic field • In average cosmic ray with energy 4*1019 eV will be deflected on 5 degrees and deflection decreases as 1/E at higher energies. • Models are not very good to follow individual CR at 1019 eV but at higher energies E > 1020 eV deflection is only 1-2 degrees.

  9. From G. Medina Tanco et al, astro-ph/9707041 • Protons with energy 4*1019 eV deflection in galactic magnetic field.

  10. From G. Medina Tanco et al, astro-ph/9707041 • Iron with energy 2.5*1020 eV deflection in galactic magnetic field.

  11. HiRes stereo data E> 1019 eV

  12. AGASA data E> 1019 eV

  13. Pion production n p Conclusion: proton, photon and neutrino fluxes are connected in well-defined way. If we know one of them we can predict other ones:

  14. Radio backgrounds

  15. Photon energy losses

  16. Dependence on parameters

  17. Minimal distance to sources.

  18. Maximal proton energy.

  19. Average extragalactic magnetic field.

  20. Radio background.

  21. Fit to AGASA and HiRes data

  22. Fit to AGASA data.

  23. Fit to HiRes data

  24. Exotic models?

  25. Z-burst mechanism • Resonance energy E = 4 1021 (1 eV/mn) eV • Works only if mn < 1 eV • Mean free path of neutrino is L = 150 000 Mpc >> Luniv T.Weiler, 1982 Fargion, Weiler, 1997

  26. Cross sections for neutrino interactions withrelict background n andg

  27. EGRET: diffuse gamma-ray flux The high energy gamma ray detector on the Compton Gamma Ray Observatory (20 MeV - ~20 GeV)

  28. Secondary gamma-rays obey EGRET limit O.Kalashev, V.Kuzmin, D.S. and G.Sigl, hep-ph/0112351

  29. Sources of both g and n O.Kalashev, V.Kuzmin, D.S. and G.Sigl, hep-ph/0112351

  30. FORTE and WMAP practically exclude Z-burst model D.S. and G.Sigl, hep-ph/0309328

  31. But only to explain AGASA

  32. Top-down models • Topological defects were produced in early Universe. • Today they decay through GUT-scale particles with masses 1013-15 GeV • UHECR are protons and photons from their decay. V.Berezinsky and collaborators 1980-90th, See review by G.Sigl

  33. Top-down models: disfavored by EGRET data D.S. and G.Sigl, hep-ph/0309328

  34. Top-down models: still alive with lower flux normalization

  35. Super-heavy dark matter model • Particles with mass 1012-14 GeV created in early Universe. Today they decay and produce UHECR. • Main signature: UHECR are photons. Arrival directions follow DM profile. V.Berezinsky, M.Kachelriess and A.Vilenkin; V.Kuzmin and V.Rubakov , 1997 Annihilations Disfavored by SUGAR data. Decay OK. M.Kachelriess and D.S., 2003; Kim and P.Tinyakov, 2003

  36. SHDM: photons + protons

  37. Sensitivity to fraction of photons: AGASA case ---------- ----------

  38. Sensitivity to fraction of photons: HiRes case ---------- ----------

  39. Conclusion: UHECR photons • UHECR with energies below GZK cutoff E<1020eV most probably are protons from astrophysical sources. Those protons would produce GZK neutrinos + GZK photons. • GZK photons are 0.01% – 50% fraction of UHECR depending from energy, proton spectrum, distribution of sources, extra-galactic magnetic fields, radio backgrounds. • They can be used to identify UHECR sources. • UHECR with energies E>1020eV require new physics or very extreme astrophysics. Absence of near sources in direction of highest energy cosmic rays makes possibility to have new physics practically unavoidable. • Top-down models are difavorate by existing data. Z-burst model is excluded by neutrino and CMB experiments. Measurement of photon flux or limit will critically test all those models in near future!

  40. HAPPY BIRTHDAY LEO!

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