GeoSynchrotron Radiation from Tau Neutrino Induced Shower

1. GeoSynchrotron Radiation from Tau Neutrino Induced Shower Kwang-Chang Lai collaborate with C.-C. Chen, G.-L. Lin, T.-C. Liu and J. Nam Institute of Physics, NCTU, Hsinchu, Taiwan Leung Center for Cosmology and Particle Astrophysics, NTU, Taipei, Taiwan Dept. of Phys., CYCU, 2009.04.28

2. Ultra high energy particles are detected by measuring the induced air showers. • Detecting radio emission is one way to measure the air shower. • Radio emission can be produced by charged particles gyrating the geomagnetic field. • An earth-skimmingtau neutrino will induce an air shower after turning into tau. • Resulted emission is calculated in the coherent geosynchrotron model.(Huege and Falcke, A&A, 2003)

3. Radio wave Cherenkov radiation Fluorensence light Charged particles neutrino Tau Shower

4. Air shower t1 Longitudinal distribution t2 t3 t4 t5 Shower front Shower max

5. The shower comes from em cascades of tau decay products, dominantly • We simulate electron showers at energies of 10^16.5, 10^17, 10^17.5, 10^18 and 10^18.5 eV. • These energies correspond to comogenic neutrinos. • Shower structure, angular and energy distribution, is adapted to calculate the synchrotron radiation. • The pattern of the radiation field and the radio pulse are presented.

6. Geometry y x z off distance d Front of shower max. 10km observation distance R k =1000m

7. Shower front is modeled as a part of a spherical surface. Each particle is assumed to emit radially from the center. is thus defined. So is curvature radius k. shower core emission position, k (curvature radius) Shower front p()(r) p(): particle energy distribution (r): particle lateral distribution

8. Synchrotron radiation for one particle ω, γ, ρ, θ: frequency of radiation, Lorentz factor and gyroradius, line-of-sight angle. Electron-positron pair coherence assumed.

9. Total yield by superposition over shower profile: is approximated. Electron-positron coherence helps to eliminate . p, ρ: energy distribution and lateral profile generated from simulation.

10. Shower Structure: Blue is fitting curve Red is simulated curve

11. Shower Structure:particle energy distribution

12. Shower Structure:particle energy distribution

13. Shower Struture:Angle of Emission

14. The shower comes from em cascades of tau decay products, dominantly • We simulate electron showers at energies of 10^16.5, 10^17, 10^17.5, 10^18 and 10^18.5 eV. • These energies correspond to cosmogenic neutrinos. • Shower structure, angular and energy distribution, is adapted to calculate the synchrotron radiation. • The pattern of the radiation field and the radio pulse are presented.

15. 50MHz 75MHz 100MHz d R R=10km Antenna distance d

16. d R R=10km 10^17eV 10^17.5eV 10^18eV Antenna distance d

17. Radiation Spectra R=10km d=0 10^16.5eV 10^17eV 10^17.5eV 10^18eV

18. Scaling Behavior at center d=500m d=1000m

19. Shower front is modeled as a part of a spherical surface. Each particle is assumed to emit radially from the center. is thus defined. So is curvature radius k. shower core emission position, k (curvature radius) Shower front p()(r) p(): particle energy distribution (r): particle lateral distribution

20. Shower Struture:Emission Position

21. Effect of Curvature Radius 10^18.5 eV 10^18 eV 10^17.5 eV 10^17 eV 10^16.5 eV

22. Pulse Expectation 10^17eV 10^17.5eV 10^18eV d R R=10km d=0

23. Pulse Expectation at core 500m 1000m d R R=10km Antenna distance d

24. d R Pulse Expectation 10km 15km 20km 30km 40km observation distance R Antenna distance d

25. Summary • We analyzed the radio property of tau neutrino induced shower. • Shower profile has universal features. • The universal Lorentz and lateral distributions allow to adapt fitting formulae in calculation. • The coherent geosynchrotron model, though incomplete, rendered a picture for detecting tau neutrino by radio emission. • This work provide a basis to develop a realistic simulation. • It also is a good reference for experiments design.