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Neutrinos and Ultra-High Energy Cosmic Rays

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  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. 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. INTRODUCTION

  4. Extragalactic neutrino flux? • Only ~ 20 neutrinos with energy E~ 10-40 MeV from SN 1987A

  5. 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+g-> 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. 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:

  7. High energy neutrino experiments

  8. Neutrino – nucleon cross section • Proton density np~ 1024/cm3 • Distance R~104km • Cross section snN=1/(Rnp)~10-33cm2 • This happens at energy E~1015 eV. ~E0.4

  9. Experimental detection of E<1017eV 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>1015eV • Experiments: MACRO, Baikal, AMANDA

  10. MACRO

  11. Lake Baikal First underwater telescope First neutrinos underwater 4-string stage (1996)

  12. AMANDA Super-K DUMAND depth Amanda-II: 677 PMTs at 19 strings (1996-2000) AMANDA-II

  13. Experimental detection of UHE (E>1017eV) neutrinos • Neutrinos are not primary UHECR • Horizontal or up-going air showers – easy way to detect neutrinos • Experiments: Fly’s Eye, AGASA

  14. Neutrino penetration depth

  15. Radio detection

  16. e + n  p + e- e-  ... cascade negative charge is sweeped into developing shower, which acquires a negative net charge Qnet ~ 0.25 Ecascade (GeV).  for  >> 10 cm (radio) coherence  relativist. pancake ~ 1cm thick,  ~10cm  each particle emits Cherenkov radiation  C signal is resultant of overlapping Cherenkov cones  C-signal ~ E2 nsec Threshold > 1016 eV

  17. Lunar Radio Emissions from Inter- actions of  and CR with > 1019 eV Gorham et al. (1999), 30 hr NASA Goldstone 70 m antenna + DSS 34 m antenna 1 nsec  moon Earth  E2·dN/dE < 105 eV·cm-2·s-1·sr-1 at 1020 eV GLUEGoldstone Lunar Ultra-high Energy Neutrino Experiment Effective target volume ~ antenna beam (0.3°)  10 m layer  105 km3

  18. RICE Radio Ice Cherenkov Experiment South Pole firn layer (to 120 m depth) 20 receivers + transmitters UHE NEUTRINO     DIRECTION E 2 · dN/dE < 10-4 GeV · cm-2 · s-1 · sr-1 at 1017 eV 300 METER DEPTH

  19. Acoustic detection

  20. d s P t R Particle cascade  ionization  heat  pressure wave Maximum of emission at ~ 20 kHz 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 > 1016 eV

  21. Present limits on neutrino flux g p

  22. Future limits on neutrino flux g p

  23. Mediterranean Projects 2400m ANTARES 4100m 3400m NEMO NESTOR

  24. 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 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 km3 Detector NEMO 1999 - 2001 Site selection and R&D 2002 - 2004 Prototyping at Catania Test Site 2005 - ? Construction of km3 Detector

  25. Baikal km3 project: Gigaton Volume Detector GVD

  26. IceTop AMANDA South Pole 1400 m 2400 m IceCube - 80 Strings - 4800 PMT • Instrumented volume: 1 km3 • Installation: 2004-2010 ~ 80.000 atm. per year

  27. Pierre Auger observatory

  28. Telescope Array

  29. MOUNT

  30. OWL/EUSO

  31. ANITA AntarcticImpulsiveTransientArray Flight in 2006

  32. SalSA SaltDomeShowerArray Natural Salt Domes Potential PeV-EeV Neutrino Detectors

  33. 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

  34. RICE AGASA Amanda, Baikal 2002 Anita 2004 AUGER nt AABN 2007 EUSO, OWL 2012 Auger Salsa km3 GLUE

  35. Neutrinos from UHECR protons

  36. 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 5x1018 eV < E < 5x1019 eV: protons from uniformly distributed sources like AGNs.

  37. Active galactic nuclei can accelerate heavy nuclei/protons

  38. Photo-pion production n p

  39. Parameters which define diffuse neutrino flux • Proton spectrum from one source: • Distribution of sources: • Cosmological parameters:

  40. Theoretical predictions of neutrino fluxes • WB bound: 1/E2 protons; distribution of sources – AGN; analytical calculation of one point near 1018 eV. • MPR bound: 1/E protons; distribution of sources – AGN; numerical calculation for dependence on Emax • The g-ray bound: EGRET

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

  42. Detection of neutrino fluxes: today g ni p

  43. Future detection of neutrinos from UHECR protons AGN,1/E Old sources 1/E^2

  44. Neutrinos from Active galactic nuclei

  45. 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 (106 - 1010 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 g-rays emitted within a few degrees of jet axis. Mechanisms are speculative; g-rays offer a direct probe.

  46. Neutrinos from AGN core

  47. Photon background in core • Energy scale Eg= 0.1 – 10 eV • Time variability t ~ few days or R = 1016cm • Model: hot thermal radiation. T=10 eV T=1 eV