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

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

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

How to find evidence of proton acceleration?

Neutrinos

Waxman and bahcall 1997, 1998 ｐ＋ γ→n+π ＋ π＋→μ＋ +νμπ＋→μ＋ +νμ μ ＋ →e ＋ + ν μ + ν e log E (eV ) l o g [ E N ( E ) ] erg x 100  =500 R= cm  B =0.1  e at 1Gpc by 10 5 km 2 detector Kaon-decay Pion-decay Muon-decay  t=66 msec L=1.5 x erg/s Next talk -> Murase Asano & Nagataki 2006

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

GRB spectrum ???

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

TeV Photons HESS MAGIC CANGAROO-III

Proton Cascade ｐ＋ γ→n+π ＋ →p+π 0 Asano 2005

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

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

Double break f B =1.0 Characteristic Spectrum due to Protons e-SY

Proton and muon synchrotron f B =30.0 e-SY

Proton acceleration efficiency We need ergs/Mpc 3 /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 We have assumed Up=Ue so far, but…

GRB rate

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

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

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

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

E sh -dependence

Up-dependence

Γ-dependence

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 eV CRs. (Wang et al. 2007)

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

Particle Acceleration in Winds Faster, Energetically lower

Secondary Particles Asano & Meszaros ～ 4 days integration

Secondary Photons ～ 4 days integration

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

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