1. Sergio Palomares-RuizAugust 28, 2006 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. Sergio Palomares-RuizAugust 28, 2006 HE  -rays Electromagnetic processes Hadronic processes Nuclei photodisintegration

3. Sergio Palomares-RuizAugust 28, 2006 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 (m e /m p ) 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. Sergio Palomares-RuizAugust 28, 2006 Hadronic processes Interactions with matter –  0 decay E K th = 280 MeV: at high energies it dominates over bremmstrahlung Interactions with photons –  0 decay E th = 145 MeV : high threshold

5. Sergio Palomares-RuizAugust 28, 2006 Nuclei de-excitation after photodisintegration A highly relativistic nucleus, E =  A m N, 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 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

6. Sergio Palomares-RuizAugust 28, 2006 TeV  -rays TeV ~  E  →  ~ 10 6 –10 7 Background T ~ 1-10 eV ~ 10 4 – 10 5 K Lyman  emissions from hot stars

7. Sergio Palomares-RuizAugust 28, 2006 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. Sergio Palomares-RuizAugust 28, 2006 GDR QD IAEA Photonuclear Data Library

9. Sergio Palomares-RuizAugust 28, 2006 Photodisintegration rate  = photon energy  ’ = photon energy in the rest frame of the nucleus n(  ) = photon density Single pole approximation: F. W. Stecker, Phys. Rev. 180:1264, 1970

10. Sergio Palomares-RuizAugust 28, 2006 If R A is weakly dependent on energy for 10 6 <  < 10 7 → photon spectra with same index as spectra of parent nuclei in the PeV/nucleon energy region lower limit on the resulting  -ray energy: NO low energy counterpart R A almost constant for  ~10 6 – 10 7 S. Karakula, G. Kociolek, I. V. Moskalenko and W. Tkaczyk, Astrophys. J. Suppl. 92:481, 1994 L. A. Anchordoqui, J. F. Beacom, H. Goldberg, SPR and T. J. Weiler, in preparation

11. Sergio Palomares-RuizAugust 28, 2006 HE neutrinos Hadronic processes Nuclei photodisintegration

12. Sergio Palomares-RuizAugust 28, 2006 Interactions with matter – charged  decay Interactions with photons –charged  decay Hadronic processes

13. Sergio Palomares-RuizAugust 28, 2006 Neutron lifetime: For E N ~ 10 6 GeV →  N ~ 10 pc For a source distance d ~ 1 kpc → All neutrons will  -decay en route to Earth → Guaranteed flux of antineutrinos Neutron decay from nuclei photodisintegration

14. Sergio Palomares-RuizAugust 28, 2006 Approximations: –monochromatic e spectrum from  -decay –Replace neutron decay probability 1 – e -d/  N by a step function at E N max ~ 10 8 – 10 9 GeV Relation between  -ray and e emissivities: for a power-law spectrum / E -  Neutron decay from nuclei photodisintegration 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. Sergio Palomares-RuizAugust 28, 2006 Photodisintegration vs  decay TeV  -rays: TeV e : L. A. Anchordoqui, J. F. Beacom, H. Goldberg, SPR and T. J. Weiler, in preparation

16. Sergio Palomares-RuizAugust 28, 2006 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