1. THE ORIGIN OF COSMIC RAYS Pasquale Blasi Fermilab/Center for Particle Astrophysics INAF/Arcetri Astrophysical Observatory, Italy Pasquale Blasi Fermilab/Center for Particle Astrophysics INAF/Arcetri Astrophysical Observatory, Italy

3. Early History of Cosmic Rays

4. Ionized by what? 1895: X-rays (Roengten) 1895: X-rays (Roengten) 1896: Radioactivity (Becquerel) 1896: Radioactivity (Becquerel) But ionization remained, though to a lesser extent, when the electroscope was inserted in a lead or water cavity But ionization remained, though to a lesser extent, when the electroscope was inserted in a lead or water cavity

5. Victor F. Hess: the 1912 flight Wulf Electroscope (1909) + + 6am August 7, 1912 Aussig, Austria

6. COSMIC Rays

7. Millikan Theory Cosmic Rays (as Millikan named them) are gamma rays as the birth cry of elements heavier than hydrogen Millikan fit: 300 1250 2500 g/cm 2 26 110 220 MeV 4 p → He ΔM=27 MeV OK 14 p → N ΔM=108 MeV OK 12 p → CΔM=85 MeV ? 16 p → O ΔM=129 MeV OK 28 p → SiΔM=150 MeV May be

8. But birth cries do not go through lead! Bruno Rossi had performed several experiments with his coincidence Geiger counters and found that CR could penetrate even 1m of lead G G G Lead COSMIC RAYS Must have ENERGY > GeV COSMIC RAYS Must have ENERGY > GeV

9. Definitely charged… D. Skobeltsyn: picture of cosmic ray event in cloud chamber with B-field (1927)

10. 1930: B. Rossi in Arcetri predicts the East-West effect 1930: B. Rossi in Arcetri predicts the East-West effect 1932: Carl Anderson discovers the positron in CR 1932: Carl Anderson discovers the positron in CR 1934: Bruno Rossi detects coincidences even at large distance from the center...first evidence of extensive showers ! 1934: Bruno Rossi detects coincidences even at large distance from the center...first evidence of extensive showers ! 1937: Seth Neddermeyer and Carl Anderson discover the muon 1937: Seth Neddermeyer and Carl Anderson discover the muon 1938-39: Auger detects first extensive air showers with energy up to 10 13-14 eV 1938-39: Auger detects first extensive air showers with energy up to 10 13-14 eV 1940’s: Boom of particle physics discoveries in CR 1940’s: Boom of particle physics discoveries in CR 1962: UHECRs by Linsley & Scarsi 1962: UHECRs by Linsley & Scarsi

11. The Spectrum of Cosmic Rays Knee 2 nd knee? Dip/Ankle GZK? 140 GeV 2.5 TeV 20 TeV 100 TeV 450 TeV

12. Spectra of different species Protons Hörandel‘s model (2003)

14. Supernovae and CR RATE OF SUPERNOVAE: 1/100 years Typically E kin ~ 10 51 erg goes to KINETIC ENERGY OF EJECTA. This corresponds to: Efficiency of conversion to CR ~ 10-20 % BUT HOW DOES THE CONVERSION OCCUR?

15. Shocks MASS OF THE EJECTA: M ej FREE EXPANSION VELOCITY: SEDOV PHASE: The sound speed in the ISM is about 10 6 cm/s STRONGSHOCK

16. Collisional vs Collisionless

17. First order Fermi Acceleration: TEST PARTICLE THEORY U 2 U 1 Downstream Upstream In a few interaction lengths particles are isotropized namely the plasma is heated T2T2 T1T1 U2U2 U1U1 WHAT HAPPENS TO A TEST PARTICLE THROWN IN THE SHOCKED REGION?

18. 1 st order Fermi Acceleration (Krimsky 1977, Bell 1978) P return probab. G energy gain

19. At zero order the distribution of (relativistic) particles at the shock is isotropic: f(μ)=constant Return Probability and energy gain THE SPECTRUM OF ACCELERATED PARTICLES IS A POWER LAW WITH UNIVERSAL SLOPE RETURN PROBABILITY FROM DOWN ENERGY GAIN PER CYCLE ONLY DEPENDS UPON THE COMPRESSION FACTOR!!!!!

20. Problems with test particle theory Efficiency requested 10-20% and yet no dynamical reaction??? Efficiency requested 10-20% and yet no dynamical reaction??? Why do particles go back to the shock anyway ? Why do particles go back to the shock anyway ? Maximum energy exceedingly low! Maximum energy exceedingly low! Injection problem and connection to the total energy/heating Injection problem and connection to the total energy/heating

21. Why do particles return to the shock? B0B0 BxBx ByBy B x,y <<B 0 z Clearly the mean displacement vanishes:

22. Diffusion Resonant k Power in the modes with k Diffusion in angle Charged particles propagate diffusively in a background of Alfven waves

23. The Maximum Energy problem If the background of Alfven waves is the same responsible for diffusion of CR in the Galaxy then MAX ENERGY OF ORDER 1 GeV or LESS !!! ACCELERATION WORKS ONLY IF SOMETHING ELSE PROVIDES A BACKGROUND OF STRONGER WAVES

24. Non-Linear Theory of Particle Acceleration aims at: Determining the dynamical reaction of accelerated particles Determining the dynamical reaction of accelerated particles Determining the background of Alfven waves due to accelerated particles Determining the background of Alfven waves due to accelerated particles

25. Dynamical Reaction of Accelerated Particles PRECURSOR Undisturbed Medium Shock Front v subshock Precursor Conservation of Momentum Transport equation for cosmic rays SUBSHOCK Velocity Profile

26. Cosmic Ray self-induced scattering: a primer Small perturbations in a magnetized medium made of electrons and protons simply give ALFVEN WAVES WHAT HAPPENS WHEN THERE IS A SHOCK AND IT IS ACCELERATING COSMIC RAYS? SHOCK B V s >>V A

27. Non Resonant Instability of Vlasov modes Vs=10 9 cm/s Vs=5 10 8 cm/s Vs=2 10 8 cm/s Vs=10 8 cm/s PB and Amato 2007 Bell 2004

28. Chandra Cassiopeia A Chandra SN 1006 Exciting News! CAS-ASN1006 First detection of amplified magnetic field in SNR First detection of amplified magnetic field in SNR

29. 240μG 360μG 240μG 360μG Rim A Rim B Berezhko, Voelk and ksenofontov 2005 upstream and further compressed at the subshock by ~3

30. Implications of B-field amplification p max /mc 10 7 10 6 10 5 10 4 M0M0 50 100 150 200 M0M0 MAXIMUM MOMENTUM PROTON KNEE PB, Amato & Caprioli, 2007 Bohm Diff without B-amplification

31. The case of RXJ1713 HESS Collaboration

32. Multifrequency Modeling RADIO X-RAYS Berezhko & Völk (2006)

33. Morlino, Amato & PB 2008 RXJ1713 E max EπEπ ν syn ν ICS B-Fields Compress.

34. The End of Galactic CR  The levels of B-field observed allow for proton acceleration in a SNR up to ~3 10 6 GeV  A nucleus with charge Z would acquire ~3 Z 10 6 GeV  For an Iron nucleus this would lead to ~10 8 GeV=10 17 eV END OF THE GALACTIC SPECTRUM AROUND 10 17 eV and Fe Dominated!

35. Anisotropies and chemicals Getting Heavier ?

36. THE TRANSITION FROM GALACTIC TO ULTRA HIGH ENERGY COSMIC RAYS

37. An ankle or a twisted ankle? Gal-CR extend to >10 19 eV and are Fe-dominated Gal-CR extend to >10 19 eV and are Fe-dominated The ankle is due to a steep Gal-CR spectrum crossing the flat Extra- Gal Spectrum The ankle is due to a steep Gal-CR spectrum crossing the flat Extra- Gal Spectrum The chemical composition should be heavy up to about 10 19 eV The chemical composition should be heavy up to about 10 19 eV Ankle

38. PROPAGATION OF EXTRAGALACTIC COSMIC RAYS

39. Cosmic Ray Energy Losses UNIVERSE EXPANDS BETHE-HEITLER PAIR PRODUCTION PHOTO-PION PRODUCTION

40. Transition through the Pair Production Dip

41. Pair-Production Dip Aloisio, Berezinsky, PB, Gazizov, Grigorieva, Hnatyk, 2007 Berezinsky et al 2005

42. The Dip Aloisio, Berezinsky, PB, Gazizov, Grigorieva, Hnatyk 2007 Berezinsky et al 2005

43. The effect of chemicals No more than ~15% of Helium is allowed at the source…still compatible with primordial abundances HeliumIron

44. Mixed Composition at the source Allard, Parizot and Olinto, 2005-2007

45. Penetration Depth Aloisio, Berezinsky, PB, Ostapchenko, 2007 D DIPANKLE

46. Penetration depths Kampert 2008

47. Ultra-High Energy Cosmic Rays HiResPAO The GZK feature seems to be present and it’s at the “right” place

48. The Spectrum Solid: γ=2.6 m=0 Emax=10 21 eV Dashed: γ=2.6 m=0 Emax=10 20 eV Dotted: γ=2.4 m=4 Emax=10 21 eV Q(E,z)~E -γ (1+z) m exp(-E/E max ) A flux suppression is present at the same energy but for different reasons

49. CR Astronomy with PAO CORRELATION OF THE ARRIVAL DIRECTIONS LOCAL DISTRIBUTION OF MATTER WITH THE LOCAL DISTRIBUTION OF MATTER FIRST DETECTION OF ANISOTROPIES !!! UHECR are extragalactic after all !

50. Anisotropy and Chemical Composition Xmax compatible with anisotropies? Xmax compatible with anisotropies? May be there is something new to learn on cross section/multiplicity at ~300 TeV c.m. May be there is something new to learn on cross section/multiplicity at ~300 TeV c.m. A proton dominated composition at the highest energies is common to all models of UHECR, but… A proton dominated composition at the highest energies is common to all models of UHECR, but…

51. Limits on the local B-field Galactic Magnetic Field Galactic Magnetic Field Intergalactic Magnetic Field Intergalactic Magnetic Field (1-3) Z deg in the halo 30 Z deg in the disc THE LOCAL UNIVERSE IS NOT STRONGLY MAGNETIZED

52. AGN as sources? Image courtesy of NRAO/AUI

53. Let’s do the numbers A simple estimate of the conditions in the knots The Poynting flux would be

54. Particle Acceleration at Relativistic Shocks? c/3 c At the lowest level there is no acceleration, BUT… If there is strong turbulence: Spectrum with γ~2.2-2.3 BUT NOT UNIVERSAL! In general steep spectra come out…but there are exceptions…

55. Auger North The UHE cosmic ray sky may be anisotropic on a large scale: FULL SKY COVERAGE The UHE cosmic ray sky may be anisotropic on a large scale: FULL SKY COVERAGE DISCOVER THE SOURCES requires even larger exposures: 7 times Auger South is the plan DISCOVER THE SOURCES requires even larger exposures: 7 times Auger South is the plan Measuring the spectrum of one source is a breakthrough to look forward to Measuring the spectrum of one source is a breakthrough to look forward to UHE Neutrinos UHE Neutrinos

56. A New Type of Astronomy PB & De Marco 2003 E>10 20 eV CRITICAL EXPOSURE… Source Spectrum

57. SummarySummary  Direct measurements are reaching the knee!  Spectra of different chemical species!  Discovery of B-field amplification → acceleration in SNR  A new standard model with end of galactic CR at 10 17 eV  Transition GALACTIC→EXTRA-GALACTIC  PAO Anisotropies and Spectrum  Auger North as a UHECR telescope and as a tool to test interactions at 300 TeV c.m.