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Nuclei

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Nuclei

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  1. GZK 40: The 3rd International Workshop on THE HIGHEST ENERGY COSMIC RAYS AND THEIR SOURCES INR RAS, Moscow, 17 May 2006 Nuclei As Ultra High Energy Cosmic Rays Oleg Kalashev*UCLA, INR RAS * e-mail: kalashev@physics.ucla.edu

  2. Overview Motivation Propagation of protons and nuclei compared Typical propagated spectrum of protons and nuclei Fitting AGASA and HiRes spectra Conclusion GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  3. GZK problem • All experiments have registered events above 100 EeV • HiRes is claimed to be consistent with GZK cutoff provided that UHECR sources are close enough, however no evident sources has been found yet within GZK sphere GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  4. Possible solutions GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  5. Top-Down models: Possible solutions • Topological defects • Z-burst GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  6. Top-Down models (disfavored?) : AGASA muon measurements Possible models • Topological defects • Z-burst γ-ray fraction predicted is close to experimental bounds! Gelmini, Kalashev, Semikoz astro-ph/0506128 Current experimental limitations on γ ray flux on 95% CL: AGASA, Yakutsk combined (astro-ph/0601449 G.I.Rubtsov et al) 36% above 100EeV Pierre-Auger (M.Risse, ICRC 2005) 26% above 10EeV GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  7. Top-Down models (disfavored?) : Possible models • Topological defects • Z-burst Acceleration (bottom-up) models: GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  8. Top-Down models (disfavored?) : Possible models • Topological defects • Z-burst Acceleration (bottom-up) models: + Don’t require new physics GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  9. Top-Down models (disfavored?) : Possible models • Topological defects • Z-burst Acceleration (bottom-up) models: + Don’t require new physics _ Hard to achieve energies above 100 EeV (possibly extreme astrophysics needed) GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  10. Top-Down models (disfavored?) : Possible models • Topological defects • Z-burst Acceleration (bottom-up) models: • protons • nuclei GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  11. Top-Down models (disfavored?) : Possible models • Topological defects • Z-burst Acceleration (bottom-up) models: • protons • Most natural UHECR candidate as most abundant element in the universe • nuclei GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  12. Top-Down models (disfavored?) : Possible models • Topological defects • Z-burst Acceleration (bottom-up) models: • protons • Most natural UHECR candidate as most abundant element in the universe • nuclei • More efficient acceleration and isotropisation GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  13. Propagation of Ultra High Energy Cosmic Rays GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  14. Propagation of Ultra High Energy Cosmic Rays A. Uryson – next talk GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  15. Main Factors influencing UHECR propagation ? Radio background (RB) Pair production e, γ ? ICS, e+e- production synchrotron Microwave Photon Background (MWB)  & e+e- production Random Extragalactic Magnetic Field (EGMF) 10-12-10-9 G p, n  , e+e- ,photodisintegration deflection IR/Optic radiation photodisintegration Nuclei GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  16. Simulating UHECR propagation Photodisintegration F.Stecker et al. Astrophys.J. 512 (1999) 521-526. E.Khan et al. Astropart.Phys. 23 (2005) 191-201 e+e- pair production M.J.Chodorowski et al. Astrophys.J.400,181(1992)  production A.Mucke et al.,Comp.Phys.Comm.124,290(2000) Extragalactic magnetic field K.Dolag et al., ICRC 2003 proceedings Sigl et al. astro-ph/0309695 Infrared background F.Stecker et al. astro-ph/0510449 GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  17. Energy loss length - Fe GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  18. Energy loss length – Fe and p GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  19. F(E, z) = f E-α(1+z)3+mΘ(Emax- E) Θ(z-zmin) Θ(zmax-z) Phenomenological source model z – red shift,Θ(x)-step function, Emax= Z Σmax, Z- electric charge GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  20. Protons F(E, z) = f E-α(1+z)3+mΘ(Emax- E) Θ(z-zmin) Θ(zmax-z) Dependence on  Emax= 6 x 1020 eV m = 0 zmin = 0 Best fit (HiRes) α= 2.6 GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  21. Fe primaries F(E, z) = f E-α(1+z)3+mΘ(Emax- E) Θ(z-zmin) Θ(zmax-z) Dependence on  Σmax= 6 x 1020 eV m = 0 zmin = 0 Best fit (HiRes) α= 2.4 GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  22. Protons F(E, z) = f E-α(1+z)3+mΘ(Emax- E) Θ(z-zmin) Θ(zmax-z) Dependence on Emax α= 2 m = 0 zmin = 0 GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  23. Fe primaries F(E, z) = f E-α(1+z)3+mΘ(Emax- E) Θ(z-zmin) Θ(zmax-z) Dependence on Emax α= 2 Emax=26 x m = 0 zmin = 0 GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  24. Protons F(E, z) = f E-α(1+z)3+mΘ(Emax- E) Θ(z-zmin) Θ(zmax-z) Dependence on Zmin α= 2.65 Emax= 3 x 1020 eV m = 0 GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  25. He primaries F(E, z) = f E-α(1+z)3+mΘ(Emax- E) Θ(z-zmin) Θ(zmax-z) Dependence on m α= 2.3 Emax= 5 x 1021 eV zmin = 0 GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  26. Composition of the propagated cascade Nuclei with E > 10-100 EeV are subjected to photodisintegration Even if primary source composition consisted of single atomic number the propagated spectrum should contain products of photodisintegration Photodisintegration kinematics mA, m A’, mp >> k ~ 10 MeV k – background photon energy in the nucleus rest frame γ= const kth =f(γ, A) -photodisintegration chain continues EA` = EA A`/A γ= const GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  27. Fe primaries F(E, z) = f E-α(1+z)3+mΘ(Emax- E) Θ(z-zmin) Θ(zmax-z) Composition dependence on Emax Σmax α= 2 Fe m = 0 zmin = 0 Mean atomic number <A> in the cascade <A> ≡Σ Ai Fi / Ftot Fi–flux of Ai GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  28. Fe and O primaries F(E, z) = f E-α(1+z)3+mΘ(Emax- E) Θ(z-zmin) Θ(zmax-z) Composition dependence on Emax Σmax α= 2 Fe m = 0 Fe zmin = 0 Mean atomic number <A> in the cascade O <A> ≡Σ Ai Fi / Ftot Fi–flux of Ai GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  29. Fe and O primaries F(E, z) = f E-α(1+z)3+mΘ(Emax- E) Θ(z-zmin) Θ(zmax-z) Composition dependence on Emax Σmax α= 2 Fe m = 0 Fe zmin = 0 Mean atomic number <A> in the cascade O <A> ≡Σ Ai Fi / Ftot Fi–flux of Ai GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  30. Source model F(E, z) = f E-α(1+z)3+mΘ(Emax- E) Θ(z-zmin) Θ(zmax-z) (1) Fitting experimental spectra* + FLEC(E) = fo (E/Eo)-βexp(-E/Eo) where β = 2.7, Eo = 10 EeV, fo – free normalization parameter Lower energy component (LEC) if needed (2) The fit is done above 3 EeV Here we assume that LEC has galactic origin and so we neglect propagation effects, however one can show that spectrum of the form close to (2) can be obtained as a result of propagation of extragalactic protons or nuclei from the source like (1). *O. Kalashev, J. Lee, K. Arisaka, G. Gelmini work in preparation GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  31. Proton source + LEC α= 2.6 ; Emax= 1022eV; m=0; zmin=0 HiRes stereo and mono combined fit GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  32. Proton source + LEC α= 2.6 ; Emax= 1022eV; m=0; zmin=0 HiRes stereo and mono combined fit α= 2.1÷2.7 (α= 2.5÷2.7 if no LEC assumed) m ≤ 0 Zmin<0.01 (50Mpc) Emax≥ 1020.2eV GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  33. He source + LEC α= 2.3 ; Emax= 5x1021eV; m=0; zmin=0 HiRes stereo and mono combined fit α= 2.2÷2.3 -2≤ m ≤ 2 Emax> 1020.5eV Zmin<0.02 (100Mpc) lg(Σmax/eV) GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  34. Fe source + LEC α= 1.4 ; Emax= 2.6x1020eV; m=0; zmin=0 HiRes stereo and mono combined fit α= 1.0÷2.0 -3≤ m ≤ 3 works fine Zmin<0.05 (250Mpc) lg(Σmax/eV) Emax =1019.8-1020.5eV GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  35. Fe source + LEC α= 1.4 ; Emax= 2.6x1020eV; m=0; zmin=0 HiRes stereo and mono combined fit α= 1.0÷2.0 -3≤ m ≤ 3 works fine Zmin<0.05 (250Mpc) More heavy elements lg(Σmax/eV) Emax =1019.8-1020.5eV GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  36. Fe source + LEC α= 1.4 ; Emax= 2.6x1020eV; m=0; zmin=0 HiRes stereo and mono combined fit α= 1.0÷2.0 -3≤ m ≤ 3 works fine Zmin<0.05 (250Mpc) More protons lg(Σmax/eV) Emax =1019.8-1020.5eV GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  37. Nuclei-reach sources may explain UHECR spectrum as well as pure proton sources. Conclusions + Nuclei sources models with low enough Emax may be less limited in terms of distance to the closest source (250 Mpc compared to 50 Mpc for HiRes) +/- Lot of parameters to play with _ LEC is normally required _Composition study made so far by AGASA and HiRes does not support heavy nuclei as primaries for the showers More accurate composition study will clear the picture GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  38. GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  39. Experimental limitations Protons versus nuclei AGASA, ICRC 2005, K.Shinozaki at al GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  40. Appendix GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev

  41. AGASA fitting attempts Protons Emax= 1022eV; m=0; zmin=0 Iron Emax= 2.6x1020eV; m=0; zmin=0 GZK 40, INR RAS, Moscow, 17 May 2006 Oleg Kalashev