10 18 eV Neutrinos associated with UHECR ( >10 19 eV ) sources
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Transcript of 10 18 eV Neutrinos associated with UHECR ( >10 19 eV ) sources
1018eV Neutrinos associated with UHECR (>1019eV) sources
Zhuo Li (黎卓 )Peking University, Beijing
Collaborators: Eli Waxman & Liming Song
Li & Waxman, arXiv:0711.4969
Why EeV neutrino
• To directly identify CR sources• Neutrino
– Pointing to the source– Avoiding absorption
• 1018eV– Primary >1019eV
HE Neutrinos from CR accelerators
-production in accelerators:– acc. p’s; acc. e’s : synchrotron/IC photons
• If all p energy converted to (in the source)
• Waxman-Bahcall Bound for sources optically thin to p:
GZK
0/21
21
Hcjj
p
Waxman & Bahcall 1999
eeNpp ;)(
sr scmGeV10
dd
282
j
UHECR source: acceleration
GRB HE ’s: p interaction
→(~10-8s)
→ee (~10-6s)
-resonance: 1 MeV 1014eV.
pp=0.2GeV=0.2GeV2222
pp
Spectral cutoff: EM cooling
100TeV ~1PeV
f
Neutrino energy
n• For >10PeV protons, the
fraction of total energy loss
• Suppressed by pi+/mu+ EM energy losslife, tcool1/
[Kashiti & Waxman 2005;Rachen & Meszaros 1998]
[Waxman & Bahcall 1997]
No UHE neutrinos, how to identify UHECR sources?
EeV neutrinos: 0-induced
100TeV 1PeV
f
WB bound: f
Prompt~10sec
No cooling suppression;3% WB bound
1EeV
HE ’s from neutral 0 production• Processes
e
e
e
pp
e
np
cmb
0
0
[Li & Waxman 2007b]
EM cooling suppression
no cooling suppression
eV110
)()( 19
cmb
22
zzTcm
CMB
• Q1: suppressed by e+- production?
• Q2: deflected by IGM field (hence delayed)?
[Li & Waxman 2007b]
eecmb
cross section -1, similar above threshold
n+2
CMB peak
e+- thr. +- thr.=1019-20eV, /e=(3-10)%
ms )cm10/()G10/(1
/
degree )G10/(10
)s102( /
2729
2
98
6
B
ct
B
tcmeBt
B
Q3: HE ’s escape from source?
• Attenuated by e+- production in source – low energy break– KN suppression of cross section
• Strong synchrotron absorption below keV
• Conclusion: >10PeV photons don’t suffer attenuation
[Li & Waxman 2007b]
[Li & Waxman 2007a]
[Li & Song 2004]
dn/d
~1keV ~1MeV
EeV neutrinos: a new channel
0.03
100TeV 1PeV
0.2
WB bound
1EeV
[Li & Waxman 2007b]
1
20/km2yr1km2 experiment
association (time/direction): directly identify sources
• Coherence radio Cerenkov:
• ANITA (balloon)• ARIANNA (array)
– ~1/yr expected
[Barwick 2007]