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Neutrinos as probes of ultra-high energy astrophysical phenomena

This article explores the use of neutrinos as probes to study high-energy astrophysical phenomena, focusing on their sources, production, and detection. It discusses the observation of high-energy particles and radiation indicative of high-energy processes, as well as the potential existence of hidden sources.

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Neutrinos as probes of ultra-high energy astrophysical phenomena

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  1. Neutrinos as probes of ultra-high energy astrophysical phenomena Jenni Adams, University of Canterbury, New Zealand

  2. Neutrino sources 10-40 MeV GeV – 10sTeV up to 10 MeV J. Becker Phys. Rep. 458

  3. How do we know there are high energy astrophysical phenomena? • Observe high energy particles • Observe radiation that is indicative of high energy processes • There might be hidden sources…

  4. Cosmic messengers

  5. Astroparticle physics Neutrino astrophysics astroparticle physics High energy photon astrophysics Cosmic ray astrophysics

  6. Origin of the ultra-high energy cosmic rays? ?

  7. How do we accelerate a particle? • Fermi Acceleration

  8. How do we accelerate a tennis ball? • Not with a steady tennis racket!

  9. Need a moving racket

  10. Back to particles… ball ↔ charged particle racket ↔ magnetic mirror

  11. Fermi Acceleration • 2nd Order: randomly distributed magnetic mirrors slow and inefficient • 1st Order: acceleration in strong shock waves

  12. Hillas Plot What condition is used to estimate the maximum energy which can be obtained from a given site? The gyroradius is less than the linear size of the accelerator E18max=bsZBR

  13. Auger sky map • At energies > 6 X 1019 eV can get indications of origin (why not at lower energies?) • significance reduced in larger data set…?

  14. How do we know there are high energy astrophysical phenomena? • Observe high energy particles • Observe radiation that is indicative of high energy processes • There might be hidden sources…

  15. Non-thermal radiation – what do we mean by non-thermal?

  16. Nature’s accelerators

  17. Information from Gamma-Rays • Lots of sources identified • Morphology of galactic sources resolved • but most sources can be described by leptonic models as well as hadronic

  18. Why detect neutrinos? Source of the highest energy cosmic rays

  19. Animation generated with povray Neutrino production • p + p or p +  give pions which give neutrinos eg. p +  + n/0 p • +  +  e+e  • 0  (E~TeV)

  20. Why detect neutrinos? Figure: Wolfgang Wagner, PhD thesis

  21. BL Lac Object Krawczynski et al., ApJ 601 (2004)

  22. Accidentally discovered by the military Vela satellites in the late 1960’s = Short, intense, eruptions of high energy photons, with afterglow detected in X-ray to radio Isotropic distribution in the sky Bimodal distribution of burst times Non-thermal photon spectrum Energy output of 1051 erg to 1054 erg

  23. Progenitors • Long duration bursts result from collapse of massive star to black hole • GRB030329 observed by HETE II linked to type 1C Supernova • Long duration bursts in galaxies with young massive stars • Short duration bursts result from collision of some combination of black holes and neutron stars • GRB050509B observed by Swift with limited afterglow • Appears to have occurred near a galaxy with old stars • Theories may be rewritten by Swift observations • 050502B X-ray spike after burst, indications of multiple explosions

  24. Fireball Model Radiation dominated soup of leptons and photons implied by high optical depth Radiation pressure drives relativistic expansion of material outward M. Aloy et al. ApJL2000

  25. Afterglow g-rays Inner Engine Relativistic Wind Internal Shocks External Shock But observed spectrum is non-thermal and significant energy is expected to be transferred to the baryonic content in the wind

  26. Shock fronts Prompt g–ray emission produced by dissipation of fireball kinetic energy in internal shocks - supported by microstucture Afterglow produced in external shocks – softened spectrum due to decreasing Lorentz factor

  27. Burst spectrum Band et al., ApJ 413 (1993)   = -0.968 ± 0.022   = -2.427 ± 0.07 b = 149.5 ± 2.1 keV b GRB1122

  28. Burst spectrum Inverse Compton scattering or cooling of electrons at high energies  Synchrotron radiation from accelerated electrons   ~ - 1  ~ -2 b = 100 – 300 keV b

  29. Example of neutrino spectrum for high energy astrophysical object – GRB n Spectrum

  30. Neutrino production • p + p or p +  give pions which give neutrinos eg. p +  + n/0 p • +  +  e+e  • 0  (E~TeV)

  31. Example of neutrino spectrum

  32. GRB n Spectrum (II) • Highest energy pions lose energy via synchrotron emission before decaying reducing the energy of the decay neutrinos • Effect becomes important when the pion lifetime is comparable to the synchrotron loss time • Neutrino spectrum steepens by a power of two after this second break energy

  33. bn an bn-2

  34. fp: fraction of proton energy going into pions GRB n Spectrum (III) ax 50%charged pions, 25% per particle fe: fraction of electron to proton total energy

  35. Animation generated with povray Neutrino production • p + p or p +  give pions which give neutrinos eg. p +  + n/0 p • +  +  e+e  • 0  (E~TeV)

  36. Neutrino sources 10-40 MeV GeV – 10sTeV up to 10 MeV J. Becker Phys. Rep. 458

  37. HE Neutrino probes of fundamental physics

  38. in proportion Other neutrino detectors Super Kamiokande SNO

  39. Neutrino telescopes around the globe Lake Baikal ANTARES NEMO NESTOR KM3NET DUMAND AMANDA, RICE, IceCube, ANITA

  40. Muon – IC 40 data Topological Flavour Identification • nm produce long m tracks • Angular resolution ~ 10 • ne CC, nx NC cause showers • ~ point sources ->’cascades’ • Good energy resolution • nt ‘double bang events • Other nt topologies under study ne (cascade)simulation 16 PeV nt simulation

  41. Neutrino-nucleon cross-section

  42. Earth becomes opaque for neand nm note: angle from nadir

  43. Coming to a cinema (conference, journal) near you soon… Neutrinos Astrophysical neutrinos caught

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