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High Energy Cosmic Rays
Eli WaxmanWeizmann Institute, ISRAEL
Cosmic ray flux and Composition
E [GeV]
log [dJ/dE]
1 106 1010
E-2.7
E-3
Heavy Nuclei
Protons
Ucr(1GeV)=1 eV/cm3
Galactic plane enhancement
Isotropy
Galactic
X-Galactic)?(
[Blandford & Eichler, Phys. Rep. 87; Axford, ApJS 94; Bird et al. 94; Nagano & Watson, Rev. Mod. Phys. 00; Abu-Zayyad et al. 01]
Lighter
Composition
HiRes/MIAFly’s Eye [Abu-Zayyad et al. 01]
[Bird et al. 94]
Acceleration Problem
]K. Arisaka 02[
X-Galactic Ultra High Energy p
• High energy, XG sources existp (pN) ’s e’s, ’s
• UHE p flux Handle on flux, detector size
• Prime telescope motivation: Identify UHE p source(s)
The Data
Data- Calibrated at 1019eV
Model• Fly’s Eye fit for Galactic heavy (<1019eV): JG~E-3.50
• X-Galactic protons: Generation spectrum (shock acceleration):
Generation rate (GRB motivated):
Redshift evolution ~ SFR (GRB motivated).
;2,/ nddn nppp
[EW 95]
;yrMpc
erg103
344
0
eV10
eV10
21
19
zp
ppp d
ndd
R
Model vs. DataX-G Model: 2n yr;erg/Mpc105.3 344 R
]Bahcall & EW 02[
Ruled out 7
Data/Model consistency
• Define:
• 1019eV to 1020eV:
Data (YK,AG,FE,HR) and model consistent with
XG protons, + GZKyrMpc
erg108.0
3442
p
pp d
nd
ji Modelij
ModelijijModel
ji HRij
HRijijHR n
nnNs
n
nnNs
, ,
2,12
, ,
2,12 ~
;
36~
,20.1;26,06.1 22 NsNs ModelHR
Conclusions are Robust 2.1n yr;erg/Mpc100.3 344 R
A note on GRBs• Energy generation rate:
• Proton acceleration: Ep,max ~ 1021 eV
Claims for Ep,max << 1021 eV - irrelevant for the
model (May be valid for “external shocks” only)
• For more: See talk by P. Meszaros and Lec. Notes Phys. review (astro-ph/0103186)
yrMpc
erg103.1erg105.2
yrGpc
5.0
energy photon x MeV rate GRB
34453
3
2
e
ee d
nd
[Frail et al. 01; Schmidt 01]
Summary• Yakutsk, Fly’s Eye, HiRes: Consistent with
XG protons: + GZK
(Robust; Consistent with GRB model predictions [see talk by P. Meszaros])• AGASA (25% of total exposure): Consistent below 1020eV Excess above 1020eV: 2.2+/-0.8 8
observed New source/ New physics/ 25% energy Local inhomogeneity over-estimate
• Need: Hybrid 1018eV to 1020eV observations
yrMpc
erg108.0
3442
p
pp d
nd
??
Implications for telescopes
• X-Galactic sources of high energy ’s are out there
• UHE p flux constrains expected flux ~ 1 km3 scale required at 1 to 103 TeV
energies >> 1 km3 required at >>103 TeV (see J. Bahcall’s talk)
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