Gamma-ray Bursts and Particle Acceleration

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Gamma-ray Bursts andParticle Acceleration

• Katsuaki Asano
• (Tokyo Institute of Technology)

S.Inoue(NAOJ), P.Meszaros(PSU)
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Physical Condition in a Shell
?RR/G2
R
Photons Luminosity L
In the comoving frame Energy Density
Magnetic Field
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Time Scales
Let us consider a proton of 1019eV
In the comoving frame,
Acceleration Time Scale
Dynamical Time Scale
Cooling Time Scale
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How to find evidence of proton acceleration?
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Neutrinos
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Neutrinos
p??np
p?µ ?µ
µ ?e ?µ ?e
Next talk -gt Murase

• Waxman and bahcall 1997, 1998

Asano Nagataki 2006
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Photons
See e.g. Meszaros 2006, Dermer
Atoyan 2006
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GRB spectrum
???
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To catch the sign of proton acceleration

• GLAST will be Launched May in this year.
• It will observe 10 MeV - 300 GeV photons.

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TeV Photons
CANGAROO-III
MAGIC
HESS
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Proton Cascade
p??np ?pp0
Asano 2005
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Distortion due to proton cascade
Our Monte Carlo Simulation
Lepton distribution
fB1.0
Primary Electrons
Pairs from Cascade
E
e-SY
UpUe fBUB/Ue
Asano Inoue 2007
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Deviation due to Inv. Comp.
fB0.1
e-SY
No sign of proton acceleration
Asano Inoue 2007
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Double break
fB1.0
Characteristic Spectrum due to Protons
e-SY
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Proton and muon synchrotron
fB30.0
e-SY
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Proton acceleration efficiency
We have assumed UpUe 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/Uegt20. If GRB rate is 0.05
Gpc-3/yr, Up/Uegt100
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GRB rate
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Much more protons are accelerated?
Acceleration
Larmor radius?E
Just behind the shock front
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Much more protons
Proton10 x Electron
Asano, Inoue, Meszaros in prep.
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Much more protons
Proton100 x Electron
Photons from Proton cascade dominate.
See also Asano Takahara 2003
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Very Hard GRB
Kaneko et al. 2008
GLAST will find more such bursts?
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Esh-dependence
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Up-dependence
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G-dependence
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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)
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Hypernovae are Sources of 1018 eV Cosmic Rays?
SNR?
??
AGN? GRB?????
Wang et al. 2007
1020eV
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Particle Acceleration in Winds
Faster, Energetically lower
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Secondary Particles
Asano Meszaros 2008
_at_100Mpc
4 days integration
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Secondary Photons
4 days integration
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Regenerated Photons
GRB
Gamma-ray
Inv. Comp.
e e-
IR background photons
CMB photons
Razzaque et al. 2004
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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