gamma-ray bursts and particle acceleration
DESCRIPTION
Gamma-ray Bursts and Particle Acceleration. Katsuaki Asano ( Tokyo Institute of Technology ). S.Inoue ( NAOJ ) , P.Meszaros ( PSU ). Physical Condition in a Shell. ΔR=R/Γ 2. R. Photons: Luminosity L. In the comoving frame Energy Density: Magnetic Field:. Time Scales. - PowerPoint PPT PresentationTRANSCRIPT
Gamma-ray Bursts andParticle Acceleration
Katsuaki Asano(Tokyo Institute of Technology)
S.Inoue ( NAOJ ) , P.Meszaros ( PSU )
Physical Condition in a Shell
R
ΔR=R/Γ2
Photons: Luminosity L
erg/s 10L ,300 cm,10 5214 R
In the comoving frame Energy Density: Magnetic Field:
erg/cc 1034
722
cRL
U
G 860081.0 UB
Time ScalesLet us consider a proton of 1019eV
In the comoving frame,7
2
19
106.3eV10
cmp
Dynamical Time Scale: sec 11/ cR
Acceleration Time Scale: sec 4.02
eBc
cm
cR pL
Cooling Time Scale: sec 18006
22
3
Bm
cm
eT
p
How to find evidence of proton acceleration?
Neutrinos
Neutrinos
Waxman and bahcall 1997, 1998
p+ γ→n+π +
π +→ μ + +νμ
μ + → e + + νμ + νe
log [
E N
(E)]
1052erg x 100=500R=5 1014 cmB=0.1eat 1Gpcby 105 km2 detector
Kaon-decay
Pion-decay
Muon-decay
16 17 18 19 20-4
-3
-2
-1
0
1
2
3
4
5
-4
-3
-2
-1
0
1
2
3
4
5
Next talk -> Murase
Asano & Nagataki 2006
PhotonsSee 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 - 300 GeV photons.
TeV Photons
HESS
MAGIC
CANGAROO-III
Proton Cascade
p+ γ→n+π +
→ p+π0
Asano 2005
I.C.
E (eV)
E2N(E) [erg/cm2]
104 105 106 107 108 10910-5
10-4
10-3
Distortion due to proton cascade
s 1.1
100
erg 1051
t
E sh
Lepton distribution
E
Primary Electrons
Pairs from Cascade
fB=1.0
e-SY
Our Monte Carlo Simulation
Asano & Inoue 2007
Up=UefB=UB/Ue
I.C.
E (eV)
E2N(E) [erg/cm2]
104 105 106 107 108 109 101010-5
10-4
10-3
Deviation due to Inv. Comp.
s 33.0
100
erg 1050
t
E sh
fB=0.1
No sign of protonacceleration
Asano & Inoue 2007
e-SY
I.C.
E (eV)
E2N(E) [erg/cm2]
104 105 106 107 108 109 101010-5
10-4
10-3
Double break
s 12.0
300
erg 1051
t
E sh
fB=1.0
Characteristic Spectrum due to Protons
e-SY
I.C.
E (eV)
E2N(E) [erg/cm2]
Proton
Muon
Pion
104 106 108 1010 101210-6
10-5
10-4
10-3
Proton and muon synchrotron
s 033.0
1000
erg 1052
t
E sh
fB=30.0
e-SY
Proton acceleration efficiency
eV10@ 19
We need 6-8 1043 ergs/Mpc3/yr to explain UHECRs
epacc UU /ξ
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?
me/mp
Particle Number Distribution
Electron Proton
Energy (Arbitrary)0.0001 0.01 1 100
1e-06
0.0001
0.01
1 Acceleration
Larmor radius∝EJust behind the shock front
Much more protonsf() erg/cm2
Proton x10, p=2.5,Esh=1051 erg, t=0.1 s,=300, fB=1.0
Sync-e+ e-
IC-e+ e-
Sync-Sync-
[eV]100 103 106 109 1012
10-5
10-4
10-3
10-2
Asano, Inoue, & Meszaros in prep.
Proton=10 x Electron
Much more protonsf() erg/cm2
Proton x100, p=2.5,Esh=1051 erg, t=0.1 s,=300, fB=1.0
Sync-e+ e-
IC-e+ e- Sync-
IC-p
[eV]100 102 104 106 108 1010
10-4
10-3
10-2
Proton=100 x Electron
Photons from Proton cascade dominate.
See also Asano & Takahara 2003
Very Hard GRB
Kaneko et al. 2008
GLAST will find more such bursts ?
Esh-dependence
[eV]
f() [erg/cm2] Up/Ue=10, UB/Ue=1, t=0.1 s, =300
Esh=1049 erg
Esh=1050 erg
Esh=1051 erg
102 104 106 108 1010 101210-9
10-8
10-7
10-6
10-5
Up-dependence
[eV]
f() [erg/cm2] Esh=1051 erg, UB/Ue=1, t=0.1 s, =300
Up/Ue=10
Up/Ue=30
Up/Ue=100
102 104 106 108 101010-6
10-5
10-4
Γ-dependence
[eV]
f() [erg/cm2] Esh=1051 erg, Up/Ue=30, t=0.1 s, UB/Ue=1
103 106 109 101210-7
10-6
10-5
10-4
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)
Hypernovae are Sources of 1018 eV Cosmic Rays ?
1020eV
SNR ?
AGN? GRB?銀河団 ?
??
Wang et al. 2007
Particle Acceleration in Winds
Faster, Energetically lower
[eV]
f() [erg/cm2]
Initial p (dashed)
Final p/n (solid)
(solid)(dashed)
p-SY
p-IC
Hypernova
100 105 1010 1015 102010-12
10-10
10-8
10-6
Secondary ParticlesAsano & Meszaros 2008
@100Mpc
~ 4 days integration
Secondary Photons
[eV]
f() [erg/cm2]
GLAST
-decay
p-SY-SY
e-SY
MAGIC
XMM-NewtonRegenerated Photon
100 105 1010 101510-9
10-8
10-7
10-6
~ 4 days integration
Regenerated Photons
GRBGamma-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