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TeV  -rays and  from nuclei photodissociation

TeV  -rays and  from nuclei photodissociation. TeV Particle Astrophysics II 28-31 August 2006, Madison, WI, USA. in collaboration with Luis Anchordoqui, John Beacom, Haim Goldberg and Tom Weiler. HE  -rays. Electromagnetic processes. Hadronic processes. Nuclei photodisintegration.

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TeV  -rays and  from nuclei photodissociation

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  1. TeV -rays and  from nuclei photodissociation TeV Particle Astrophysics II 28-31 August 2006, Madison, WI, USA in collaboration with Luis Anchordoqui, John Beacom, Haim Goldberg and Tom Weiler

  2. HE -rays Electromagnetic processes Hadronic processes Nuclei photodisintegration

  3. Electromagnetic processes • Interactions with matter • Electron bremsstrahlung does not change the form of the initial spectrum (above ~350 MeV) • Electron-positron annihilation 10%-20% in flight: does not change the form of the initial spectrum • Interactions with photons • Inverse Compton scattering: electrons very efficient • Inverse Compton scattering: protons suppressed by (me/mp)4 • Interactions with magnetic fields • Synchroton radiation: electrons steep spectrum at low energies and flat spectrum at high energies • Synchroton radiation: protons generally inefficient process

  4. Hadronic processes • Interactions with matter • 0 decay EK th = 280 MeV: at high energies it dominates over bremmstrahlung • Interactions with photons • 0 decay Eth = 145 MeV : high threshold

  5. Nuclei de-excitation after photodisintegration I. V. Moskalenko, PhD Thesis, Moscow State University, Moscow, 1985 V. V. Balashov, V. L. Korotkikh and I. V. Moskalenko, Moscow Univ. Phy. Bull. 42: 93, 1987; 21st ICRC 2:416, 1990 S. Karakula, G. Kociolek, I. V. Moskalenko and W. Tkaczyk, 22nd ICRC 1:536, 1991; Astrophys. J. Suppl. 92:481, 1994 • A highly relativistic nucleus, E =  A mN, propagates in a photon background • Giant Dipole Resonance: ~ 10 – 30 MeV → one nucleon is emitted and the nucleus is left in an excited state • The boosted nucleus emitts n photons with E ~ MeV

  6. TeV -rays TeV ~  E→  ~ 106–107 Background T ~ 1-10 eV ~ 104 – 105 K Lyman  emissions from hot stars

  7. Photonuclear interactions • Low energy region (GDR): E < 30 MeV single nucleon emission • Medium energy region (quasi-deuteron effect): 30 MeV < E < 145 MeV multiple nucleon emission • High energy region: E > 145 MeV photomeson production

  8. IAEA Photonuclear Data Library QD GDR

  9. Photodisintegration rate = photon energy ’ = photon energy in the rest frame of the nucleus n() = photon density F. W. Stecker, Phys. Rev. 180:1264, 1970 Single pole approximation:

  10. S. Karakula, G. Kociolek, I. V. Moskalenko and W. Tkaczyk, Astrophys. J. Suppl. 92:481, 1994 If RA is weakly dependent on energy for 106 <  < 107 → photon spectra with same index as spectra of parent nuclei in the PeV/nucleon energy region RA almost constant for ~106 – 107 lower limit on the resulting -ray energy: NO low energy counterpart L. A. Anchordoqui, J. F. Beacom, H. Goldberg, SPR and T. J. Weiler, in preparation

  11. HE neutrinos Hadronic processes Nuclei photodisintegration

  12. Hadronic processes • Interactions with matter • charged  decay • Interactions with photons • charged  decay

  13. Neutron decay from nuclei photodisintegration • Neutron lifetime: • For EN ~ 106 GeV → N ~ 10 pc • For a source distance d ~ 1 kpc → All neutrons will -decay en route to Earth → Guaranteed flux of antineutrinos

  14. Neutron decay from nuclei photodisintegration • Approximations: • monochromatic e spectrum from -decay • Replace neutron decay probability 1 – e-d/N by a step function at ENmax ~ 108 – 109 GeV Relation between -ray and e emissivities: for a power-law spectrum / E- L. A. Anchordoqui, H. Goldberg, F. Halzen and T. J. Weiler, Phys. Lett. B593:42, 2004 L. A. Anchordoqui, J. F. Beacom, H. Goldberg, SPR and T. J. Weiler, in preparation

  15. Photodisintegration vs  decay • TeV -rays: • TeV e: L. A. Anchordoqui, J. F. Beacom, H. Goldberg, SPR and T. J. Weiler, in preparation

  16. Conclusions • Two well known mechanisms for generating high energy -rays: EM and hadronic • Third one: photodisintegration of nuclei followed by photo-de-excitation of the daughter nuclei • Need population of nuclei with PeV/nucleon energies and a region rich in hot stars • No change on the initial power-law index and lower limit on the resulting -ray energy • Dominant for low density ISM • Very few high energy neutrinos

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