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Gamma-ray Bursts and Particle Acceleration

This study examines the physical conditions in a shell of Gamma-ray bursts (GRBs) and the evidence of proton acceleration in GRBs. It explores the time scales and energy densities involved in the acceleration process and discusses the possible detection methods. The study also discusses the spectral characteristics of GRBs and the potential role of proton cascade in secondary emission.

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Gamma-ray Bursts and Particle Acceleration

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  1. Gamma-ray Bursts andParticle Acceleration Katsuaki Asano (Tokyo Institute of Technology) S.Inoue（NAOJ）, P.Meszaros（PSU）

  2. Physical Condition in a Shell ΔR=R/Γ2 R Photons: Luminosity L In the comoving frame Energy Density: Magnetic Field:

  3. Time Scales Let us consider a proton of 1019eV In the comoving frame, Acceleration Time Scale: Dynamical Time Scale: Cooling Time Scale:

  4. How to find evidence of proton acceleration?

  5. Neutrinos

  6. 5 5 M u o n - d e c a y 4 4 3 3 P i o n - d e c a y 2 2 ] ) K a o n - d e c a y E ( 1 1 N 5 2 1 0 e r g x 1 0 0 E 0 0 [ g G = 5 0 0 o l 1 4 R = 5 1 0 c m - 1 - 1 e e = 0 . 1 B e - 2 - 2 a t 1 G p c 5 2 b y 1 0 k m d e t e c t o r - 3 - 3 - 4 - 4 1 6 1 7 1 8 1 9 2 0 l o g E ( e V ) D t = 6 6 m s e c 5 3 L = 1 . 5 x 1 0 e r g / s Neutrinos ｐ＋γ→n+π＋ π＋→μ＋+νμ μ＋→e＋ + νμ+ νe Next talk -> Murase Waxman and bahcall 1997, 1998 Asano & Nagataki 2006

  7. Photons See e.g. Meszaros 2006, Dermer & Atoyan 2006

  8. GRB spectrum ???

  9. To catch the sign of proton acceleration • GLAST will be Launched May in this year. • It will observe 10 MeV - 300 GeV photons.

  10. TeV Photons CANGAROO-III MAGIC HESS

  11. Proton Cascade ｐ＋γ→n+π＋ →p+π0 Asano 2005

  12. Our Monte Carlo Simulation Distortion due to proton cascade Lepton distribution fB=1.0 Primary Electrons Pairs from Cascade E e-SY Up=Ue fB=UB/Ue Asano & Inoue 2007

  13. Deviation due to Inv. Comp. fB=0.1 e-SY No sign of proton acceleration Asano & Inoue 2007

  14. Double break fB=1.0 Characteristic Spectrum due to Protons e-SY

  15. Proton and muon synchrotron fB=30.0 e-SY

  16. Proton acceleration efficiency We have assumed Up=Ue so far, but… We need 6-8 1043 ergs/Mpc3/yr to explain UHECRs See e.g. Murase, Ioka, Nagataki, Nakamura 2008 We may need Up/Ue>20. If GRB rate is 0.05 Gpc-3/yr, Up/Ue>100

  17. GRB rate

  18. Much more protons are accelerated? Acceleration Larmor radius∝E Just behind the shock front

  19. Much more protons Proton=10 x Electron Asano, Inoue, & Meszaros in prep.

  20. Much more protons Proton=100 x Electron Photons from Proton cascade dominate. See also Asano & Takahara 2003

  21. Very Hard GRB Kaneko et al. 2008 GLAST will find more such bursts？

  22. Esh-dependence

  23. Up-dependence

  24. Γ-dependence

  25. Hypernova • Very bright supernova • Some associate GRBs • Progenitors may be massive stars (WR type?). • A stellar wind environment may exist around progenitors Ejecta from hypernovae may be sources of 1017-1018eV CRs. (Wang et al. 2007)

  26. Hypernovae are Sources of 1018 eV Cosmic Rays？ SNR？ ？？ AGN? GRB?銀河団? Wang et al. 2007 1020eV

  27. Particle Acceleration in Winds Faster, Energetically lower

  28. Secondary Particles Asano & Meszaros 2008 @100Mpc ～4 days integration

  29. Secondary Photons ～4 days integration

  30. Regenerated Photons GRB Gamma-ray Inv. Comp. e+ e- IR background photons CMB photons Razzaque et al. 2004

  31. Summary • GeV-TeV emissions due to protons in GRBs • Too much protons change spectra drastically • Secondary emission from hyeprnovae • X-ray due to cascade from muon decay • GeV emission from proton synchrotron • “Delayed” TeV emission

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