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

2 plan AGASA vs HiRes AGASA: spectrum vs ssa expectations for Auger AGASA vs HiRes AGASA: spectrum vs ssa expectations for Auger

3 AGASA & HiRes a factor 2 in the flux HiRes: GZK AGASA: no GZK

4 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% HiRes I AGASA 15% within limits allowed by both collaborations

5 DDM, Blasi, Olinto 2003 systematic errors (?) AGASA +15% HiRes -15% low energy less high energy how much?

6 fit uncertainties DDM, Stanev 2005 log 10  2 fit to shifted data in the range eV to eV proton propagation

7 fit uncertainties DDM, Stanev 2005 m=0, ±1 

8 statistical error in the energy reconstruction for AGASA is increased by 1 energy resolution: ±30%

9 high energy: AGASA we simulated realizations of the AGASA statistics above 4·10 19 eV (72 events) and we counted the number of events with energy above eV. 18 realizations produced 11 or more events above eV probab.: 6·10 -4 — 3.2  the same procedure applied to the AGASA-15% statistics resulted in a probability of about 1% — 2.3  accounting for the sys. errors, the AGASA result doesn’t have a high statistical significance histogram of the number of events recorded with energy above eV AGASA result (11) propagation simulation (  =2.6) GZK suppression DDM, Blasi, Olinto 2005

10 some AGASA spectra DDM, Blasi, Olinto 2005

11 high energy: HiRes we simulated realizations of the HiRes statistics above 4·10 19 eV (27 events) and we counted the number of events with energy above eV. HiRes result (1) no propagation, we used as template the AGASA measured spectrum, but for the HiRes statistics 301 realizations produced 1 or less events above eV prob.: 3% — 2  the HiRes result as well does not have a high statistical significance histogram of the number of events recorded with energy above eV

12 no strong discrepancy between AGASA and HiRes spectra

13 Small Scale Anisotropies: what can they tell us? simulation of the propagation from astrophysical point sources

14 AGASA 2pcf point sources (?) see also Finley and Westerhoff 2003 DDM, Blasi, Olinto 2005

15 AGASA multiplets B~ eV - 57 events Mpc Mpc Mpc -3 DDM, Blasi 2004

16 sources characteristics L CR = erg/yr/Mpc 3 (E>10 19 eV - from spectrum fits) n 0 = Mpc -3 (from ssa) L src = erg/s (E>10 19 eV) are these ssa for real? the significance of the AGASA result is not clear HiRes doesn’t see them some internal inconsistency

17 P:   : 3.2  3.7 AGASA spectrum discrete sources DDM, Blasi, Olinto 2005

18 arrival directions P~ DDM, Blasi, Olinto 2005

19 both the ssa and the spectrum measurement need more statistics to be conclusive and reliable

20 Auger 2pcf E> eV Mpc Mpc Mpc Mpc -3 cont. DDM, Blasi, Olinto

21 Auger 2pcf E>10 20 eV Mpc Mpc Mpc Mpc -3 cont. DDM, Blasi, Olinto

22 Auger spectrum DDM, Blasi, Olinto

23 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 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

24 Auger ICRC spectrum