1. Neutrinos and Ultra-High Energy Cosmic Rays Dmitry Semikoz MPI, Munich & INR, Moscow in collaboration with F.Aharonian, O.Kalashev, V.Kuzmin, A.Neronov and G.Sigl

2. IFIC Valencia October 22, 2002 Overview: Introduction Experimental detection of high energy neutrinos:  Under/ground/water/ice  Horizontal air showers  Radio detection  Acoustic signals from neutrinos Neutrinos from UHECR protons Neutrinos from AGN Most probable neutrino sources Neutrinos in exotic UHECR models Conclusion

3. IFIC Valencia October 22, 2002 INTRODUCTION

4. IFIC Valencia October 22, 2002 Extragalactic neutrino flux? Only ~ 20 neutrinos with energy E~ 10-40 MeV from SN 1987A

5. IFIC Valencia October 22, 2002 Why UHE neutrinos can exist? Protons are attractive candidates to be accelerated in astrophysical objects up to highest energies. Neutrinos can be produced by protons in P+P  pions or P+  pions reactions inside of astrophysical objects or in intergalactic space. Neutrinos can be produced directly in decays of heavy particles. Same particles can be responsible for UHECR events above GZK cutoff.

6. IFIC Valencia October 22, 2002 Pion production p n Conclusion: proton, photon and neutrino fluxes are connected in well-defined way. If we know one of them we can predict other ones:

7. IFIC Valencia October 22, 2002 High energy neutrino experiments

8. IFIC Valencia October 22, 2002 Neutrino – nucleon cross section Proton density n p ~ 10 24 /cm 3 Distance R~10 4 km Cross section  N =1/(Rn p )~10 -33 cm 2 This happens at energy E~10 15 eV. ~E 0.4

9. IFIC Valencia October 22, 2002 Experimental detection of E<10 17 eV neutrinos Neutrinos coming from above are secondary from cosmic rays Neutrino coming from below are mixture of atmospheric neutrinos and HE neutrinos from space Earth is not transparent for neutrinos E>10 15 eV Experiments: MACRO, Baikal, AMANDA

10. IFIC Valencia October 22, 2002 MACRO

11. IFIC Valencia October 22, 2002 4-string stage (1996) First underwater telescope First neutrinos underwater

12. IFIC Valencia October 22, 2002 AMANDA-II depth AMANDA Super-K DUMAND Amanda-II: 677 PMTs at 19 strings (1996-2000)

13. IFIC Valencia October 22, 2002 Experimental detection of UHE (E>10 17 eV) neutrinos Neutrinos are not primary UHECR Horizontal or up-going air showers – easy way to detect neutrinos Experiments: Fly’s Eye, AGASA

14. IFIC Valencia October 22, 2002 Neutrino penetration depth

15. IFIC Valencia October 22, 2002 Radio detection

16. IFIC Valencia October 22, 2002 e + n  p + e - e - ... cascade  relativist. pancake ~ 1cm thick,  ~10cm  each particle emits Cherenkov radiation  C signal is resultant of overlapping Cherenkov cones  for >> 10 cm (radio) coherence  C-signal ~ E 2 nsec negative charge is sweeped into developing shower, which acquires a negative net charge Q net ~ 0.25 E cascade (GeV). Threshold > 10 16 eV

17. IFIC Valencia October 22, 2002

18. GLUE G oldstone L unar U ltra-high Energy Neutrino E xperiment  E 2 ·dN/dE < 10 5 eV·cm -2 ·s -1 ·sr -1 Lunar Radio Emissions from Inter- actions of and CR with > 10 19 eV 1 nsec moon Earth Gorham et al. (1999), 30 hr NASA Goldstone 70 m antenna + DSS 34 m antenna at 10 20 eV Effective target volume ~ antenna beam (0.3°)  10 m layer  10 5 km 3

19. IFIC Valencia October 22, 2002 RICE R adio I ce C herenkov E xperiment firn layer (to 120 m depth) UHE NEUTRINO     DIRECTION 300 METER DEPTH E 2 · dN/dE < 10 -4 GeV · cm -2 · s -1 · sr -1 20 receivers + transmitters at 10 17 eV

20. IFIC Valencia October 22, 2002 Acoustic detection

21. IFIC Valencia October 22, 2002 d R Particle cascade  ionization  heat  pressure wave P t ss Attenuation length of sea water at 15-30 kHz: a few km (light: a few tens of meters) → given a large initial signal, huge detection volumes can be achieved. Threshold > 10 16 eV Maximum of emission at ~ 20 kHz

22. IFIC Valencia October 22, 2002 Present limits on neutrino flux  p

23. IFIC Valencia October 22, 2002 Future limits on neutrino flux  p

24. IFIC Valencia October 22, 2002 Mediterranean Projects 4100m 2400m 3400m ANTARES NEMO NESTOR

25. IFIC Valencia October 22, 2002 NEMO 1999 - 2001 Site selection and R&D 2002 - 2004 Prototyping at Catania Test Site 2005 - ? Construction of km 3 Detector ANTARES 1996 - 2000 R&D, Site Evaluation 2000 Demonstrator line 2001 Start Construction September 2002 Deploy prototype line December 2004 10 (14?) line detector complete 2005 - ? Construction of km 3 Detector NESTOR 1991 - 2000 R & D, Site Evaluation Summer 2002 Deployment 2 floors Winter 2003 Recovery & re-deployment with 4 floors Autumn 2003 Full Tower deployment 2004 Add 3 DUMAND strings around tower 2005 - ? Deployment of 7 NESTOR towers

26. IFIC Valencia October 22, 2002 Baikal km 3 project: Gigaton Volume Detector GVD

27. IFIC Valencia October 22, 2002 IceCube 1400 m 2400 m AMANDA South Pole IceTop - 80 Strings - 4800 PMT - Instrumented volume: 1 km 3 - Installation: 2004-2010 ~ 80.000 atm. per year

28. IFIC Valencia October 22, 2002 Pierre Auger observatory

29. IFIC Valencia October 22, 2002 Telescope Array

30. IFIC Valencia October 22, 2002 MOUNT

31. IFIC Valencia October 22, 2002 OWL/EUSO

32. IFIC Valencia October 22, 2002 ANITA An tarctic I mpulsive T ransient A rray Flight in 2006

33. IFIC Valencia October 22, 2002 Natural Salt Domes Potential PeV-EeV Neutrino Detectors SalSA Sal t Dome S hower A rray

34. IFIC Valencia October 22, 2002 Renewed efforts along acoustic method for GZK neutrino detection Greece: SADCO Mediterannean, NESTOR site, 3 strings with hydrophones Russia: AGAM antennas near Kamchatka: existing sonar array for submarine detection Russia: MG-10M antennas: withdrawn sonar array for submarine detection AUTEC: US Navy array in Atlantic: existing sonar array for submarine detection Antares: R&D for acoustic detection IceCube: R&D for acoustic detection

35. IFIC Valencia October 22, 2002 RICEAGASA Amanda, Baikal 2002 2004 2007 AUGER  Anita AABN 2012 km 3 EUSO, OWL Auger Salsa GLUE

36. IFIC Valencia October 22, 2002 Neutrinos from UHECR protons

37. IFIC Valencia October 22, 2002 Why neutrinos from UHE protons? All experiments agree (up to factor 2) on UHECR flux below cutoff. All experiments see events above cutoff! Majority of the air-showers are hadronic-like Simplest solution for energies 5x10 18 eV < E < 5x10 19 eV: protons from uniformly distributed sources like AGNs.

38. IFIC Valencia October 22, 2002 Active galactic nuclei can accelerate heavy nuclei/protons

39. IFIC Valencia October 22, 2002

40. Photo-pion production p n

41. IFIC Valencia October 22, 2002 Parameters which define diffuse neutrino flux Proton spectrum from one source: Distribution of sources: Cosmological parameters:

42. IFIC Valencia October 22, 2002 Theoretical predictions of neutrino fluxes WB bound: 1/E 2 protons; distribution of sources – AGN; analytical calculation of one point near 10 18 eV. MPR bound: 1/E protons; distribution of sources – AGN; numerical calculation for dependence on E max The  ray bound: EGRET

43. IFIC Valencia October 22, 2002 The high energy gamma ray detector on the Compton Gamma Ray Observatory (20 MeV - ~20 GeV) EGRET: diffuse gamma-ray flux

44. IFIC Valencia October 22, 2002 Detection of neutrino fluxes: today  i p

45. IFIC Valencia October 22, 2002 Future detection of neutrinos from UHECR protons AGN,1/E Old sources 1/E^2

46. IFIC Valencia October 22, 2002 Neutrinos from Active galactic nuclei

47. IFIC Valencia October 22, 2002 Active Galactic Nuclei (AGN) Active galaxies produce vast amounts of energy from a very compact central volume. Prevailing idea: powered by accretion onto super-massive black holes (10 6 - 10 10 solar masses). Different phenomenology primarily due to the orientation with respect to us. Models include energetic (multi-TeV), highly-collimated, relativistic particle jets. High energy  -rays emitted within a few degrees of jet axis. Mechanisms are speculative;  -rays offer a direct probe.

48. IFIC Valencia October 22, 2002

49. Neutrinos from AGN core

50. IFIC Valencia October 22, 2002 Photon background in core Energy scale E  = 0.1 – 10 eV Time variability  few days or R = 10 16 cm Model: hot thermal radiation. T=1 eV T=10 eV

51. IFIC Valencia October 22, 2002 Photo-pion production p n

52. IFIC Valencia October 22, 2002 Neutrino spectrum for various proton spectra and backgrounds 1/E 1/E 2 T=10 eV 1/E 2 T=1 eV E~10 18 eV Atm. flux

53. IFIC Valencia October 22, 2002 Most probable neutrino sources

54. IFIC Valencia October 22, 2002 Neutrino production in AGN

55. IFIC Valencia October 22, 2002 Which sources ? Blazars (angle – energy correlation)

56. IFIC Valencia October 22, 2002 Optics: SDSS. Most powerful objects are AGNs 500 sq deg of the sky, 14 million objects, spectra for 50,000 galaxies and 5,000 quasars. Distance record-holder >13,000 quasars (26 of the 30 most distant known)

57. IFIC Valencia October 22, 2002 Low energy radiation from AGN is collimated Typical gamma-factor is  Radiation is collimated in 1/  angle ~ 5 o in forward direction.

58. IFIC Valencia October 22, 2002 EGRET 3 rd Catalog: 271 sources Most of identified MeV-GeV sources are blazars

59. IFIC Valencia October 22, 2002 All TeV sources are blazars

60. IFIC Valencia October 22, 2002 Which sources ? Blazars (angle – energy correlation) Blazars should be GeV loud

61. IFIC Valencia October 22, 2002 High energy photons from pion decay cascade down in GeV region

62. IFIC Valencia October 22, 2002 EGRET 3 rd Catalog: 271 sources Only 22 sources from 66 are GeV - loud

63. IFIC Valencia October 22, 2002 Which sources ? Blazars (angle – energy correlation) Blazars should be GeV loud ‘Optical depth’ for protons should be large:  p  n  R 

64. IFIC Valencia October 22, 2002 Bound on blazars which can be a neutrino sources

65. IFIC Valencia October 22, 2002 TeV blazars does not obey last condition Indeed, in order TeV blazars be a neutrino sources:   p  n  R     n  R   p  = 10 -28 cm 2 while   = 6.65 x 10 -25 cm 2 CONTRADICTION!!!

66. IFIC Valencia October 22, 2002 Which sources ? Blazars (angle – energy correlation) Blazars should be GeV loud Optical depth for protons should be large:  p  n  R  No 100 - kpc scale jet detected (model-dependent)

67. IFIC Valencia October 22, 2002 Neutrino production in AGN

68. IFIC Valencia October 22, 2002 Collimation of neutrino flux in compare to GeV flux

69. IFIC Valencia October 22, 2002 Acceleration of protons to higher energies

70. IFIC Valencia October 22, 2002 Neutrinos from exotic UHECR models

71. IFIC Valencia October 22, 2002 Top-down models

72. IFIC Valencia October 22, 2002 Z-burst mechanism Resonance energy E = 4 10 21 (1 eV/m ) eV Works only if m   eV Mean free path of neutrino is L = 150 000 Mpc >> L univ

73. IFIC Valencia October 22, 2002 Cross sections for neutrino interactions with relict background and 

74. IFIC Valencia October 22, 2002 Problem: too high  - ray flux m  1 eV (Yoshida,Sigl,Lee,1998)

75. IFIC Valencia October 22, 2002 Possible solution: local relic overdensity but factor 20 over 5 Mpc is needed

76. IFIC Valencia October 22, 2002 Numerical simulations of the possible local neutrino over-density give factor 2-3

77. IFIC Valencia October 22, 2002 Non-uniform distribution of sources O.Kalashev, V.Kuzmin, D.S. and G.Sigl, hep-ph/0112351

78. IFIC Valencia October 22, 2002 Sources of both  and

79. IFIC Valencia October 22, 2002 X -> only (Gelmini-Kusenko model)

80. IFIC Valencia October 22, 2002

81. Conclusions Sensitivity of the neutrino telescopes will be increased in 10 3-5 times during next 10 years. Now they just on the border of theoretically interesting region. Secondary neutrino flux from UHECR protons can be detected by future UHECR experiments. Neutrino flux from AGN’s can be detected by under-water/ice neutrino telescopes. GeV-loud blazars with high optical depth for protons are best candidates for neutrino sources. Some of exotic UHECR models will be ruled out or confirmed in near future by neutrino data.

82. IFIC Valencia October 22, 2002 References: Diffuse neutrino flux. O.Kalashev, V.Kuzmin, D.S. and G.Sigl, hep-ph/0205050 Extragalactic neutrino sources. A.Neronov & D.S., hep-ph/0208248 AGN jet model. A.Neronov, D.S., F.Aharonian and O.Kalashev, astro-ph/0201410 Z-burst model. O.Kalashev, V.Kuzmin, D.S. and G.Sigl, hep-ph/0112351