combined analysis of the spectrum and anisotropies of UHECRs

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combined analysis of the spectrum and
anisotropies of UHECRs
Daniel De Marco
Bartol Research Institute University of Delaware
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plan

• AGASA vs HiRes
• AGASA spectrum vs ssa
• expectations for Auger

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AGASA HiRes
a factor 2 in the flux
HiRes GZK AGASA no GZK
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systematic errors (?)
systematic errors may be the explanation (at low
energy)
a factor 2 in the flux can be accounted for with
a systematic error in the energy determination of
about 30
AGASA
15 within limits allowed by both collaborations
HiRes I
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systematic errors (?)
AGASA 15HiRes -15
agreement_at_ low energy
less disagreement_at_ high energyhow much?
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fit uncertainties
fit to shifted data in the range 1019 eV to 1020
eV
log10?2
proton propagation
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fit uncertainties
m0, 1 ?
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statistical error in the energy reconstruction
ltn20gt forAGASA is increased by 1
energy resolution 30
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high energy AGASA
we simulated 30000 realizations of the AGASA
statistics above 41019 eV (72 events) and we
counted the number of events with energy above
1020 eV.
18 realizations produced 11 or more events above
1020 eVprobab. 610-4 3.2 ?
propagation simulation (?2.6) GZK suppression
the same procedure applied to the AGASA-15
statistics resulted in a probability of about 1
2.3 ?
AGASA result (11)
accounting for the sys. errors, the AGASA result
doesnt have a high statistical significance
histogram of the number of events recorded with
energy above 1020 eV
DDM, Blasi, Olinto 2005
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some AGASA spectra
DDM, Blasi, Olinto 2005
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high energy HiRes
we simulated 10000 realizations of the HiRes
statistics above 41019 eV (27 events) and we
counted the number of events with energy above
1020 eV.
no propagation, we used as template the AGASA
measured spectrum, but for the HiRes statistics
301 realizations produced 1 or less events above
1020 eVprob. 3 2 ?
HiRes result (1)
histogram of the number of events recorded with
energy above 1020 eV
the HiRes result as well does not have a high
statistical significance
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no strong discrepancy between AGASA and HiRes
spectra
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Small Scale Anisotropies what can they tell us?
simulation of the propagation from
astrophysical point sources
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AGASA 2pcf
point sources (?)
DDM, Blasi, Olinto 2005
see also Finley and Westerhoff 2003
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AGASA multiplets
DDM, Blasi 2004
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sources characteristics
LCR 6 1044 erg/yr/Mpc3 (Egt1019 eV - from
spectrum fits) n0 10-5 Mpc-3 (from ssa) Lsrc
2 1042 erg/s (Egt1019 eV)

• are these ssa for real?
• the significance of the AGASA result is not clear
• HiRes doesnt see them
• some internal inconsistency

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AGASA spectrumdiscrete sources
P 6 10-4 ? 2 10-4 ? 3.2 ? 3.7
DDM, Blasi, Olinto 2005
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arrival directions
P2 10-5
DDM, Blasi, Olinto 2005
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both the ssa and the spectrum measurement need
more statistics to beconclusive and reliable
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Auger 2pcfEgt4 1019 eV
DDM, Blasi, Olinto
10-6 Mpc-3 10-5 Mpc-3 10-4 Mpc-3 10-3 Mpc-3 cont.
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Auger2pcfEgt1020 eV
10-6 Mpc-3 10-5 Mpc-3 10-4 Mpc-3 10-3 Mpc-3 cont.
DDM, Blasi, Olinto
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Auger spectrum
DDM, Blasi, Olinto
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conclusions

• AGASA HiRes statistics too low to reach
  conclusions on spectrum ssa
• m ? degeneracy we need good composition
  measurements or other method to determine where
  the galcatic CRs end (ex anisotropy)
• Auger should be able to shed light on some of
  these issues

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Auger ICRC spectrum