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Ultra High Energy Cosmic Rays Anisotropies and Astrophysical Interpretation. Alessandro Cuoco, Institute for Physics and Astronomy University of Aarhus, Denmark. May 21th 2008 XXth RENCONTRES DE BLOIS. Sky Distribution.
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Ultra High Energy Cosmic Rays Anisotropies and Astrophysical Interpretation Alessandro Cuoco, Institute for Physics and Astronomy University of Aarhus, Denmark May 21th 2008 XXth RENCONTRES DE BLOIS
Sky Distribution • For E>4-5 x1019 eV galactic and extragalactic magnetic fields are negligible and charged particles propagate almost rectilinearly: is it possible UHECRs astronomy? • Energy losses impose that sources must be near (100-200 Mpc) (GZK Cutoff) • Data from AGASA (50 events)indicate an isotropic distribution (extragalactic origin) except for a small scale clustering (point sources?)…
Auger & HIRES… GZK cutoff?!?! AUGER ICRC07: Vertical+Inclined+Hybrid 6σ Feature Hires ICRC07: 5σ Feature
Looking for structures in UHECRs • World dataset of O(100) public available UHECRs, above the “rescaled” energy of 4x1019 eV (Hires Scale) • The rescaling is done a priori, to match the ankle feature in the spectrum “Both the energy dependence of the signal and its angular scale might be interpreted as first signatures of the large-scale structure of UHECR sources and of intervening magnetic fields” Can we test that? Some low-chance prob. Structure at 15o-35o!!! M. Kachelriess & D. Semikoz Astropart. Phys. 26, 10 (2006) [astro-ph/0512498]
A.C., G. Miele, P.Serpico, PLB 660:307-314,2008, arXiv:0706.2864 Possible evidence for nearby universe structures in the ultra-high energy sky ! Clustering properties agree but structures do not match…
Check with PSCz: SH model The clustering properties of the data agree wonderfully with the SH model (chance probability of obtaining similar configurations ≈ 50%) Not strange, after a look at the data Possible evidence for nearby universe structures in the ultra-high energy sky ! A.C., G. Miele, P.Serpico, PLB 660:307-314,2008arXiv:0706.2864
Auger AGNs Correlation Centaurus A 20 out of 27 events correlate with a nearby (within 75 Mpc) AGN within 3 degrees. Auger Collaboration, Science, 318 (5852), 938 (2007); Auger Collaboration, Astropart.Phys.29:188-204, (2008) [arXiv:0712.2843]. Remarkably, 5 out 7 non-correlating events lie on the galactic plane where the catalogue is incomplete and the highest deflections are expected
AGN vs Galaxies IRAS Galaxies Veron Cetty AGN Catalogue Same large scale pattern but different small scale clustering A.C., S.Hannestad, T.Haugbølle, M.Kachelriess, P.Serpico arXiv:0709.2712, ApJ .676:807,2008
Auger AutoCorrelation Auger AutoCorrelation compared to various model expectations Chance probability for various models
Extragalactic Magnetic Fields Map of deflection angles from the local clusters Dolag et al. JCAP 0501:009,2005 CR deflection in random MF: Auger Constrain on EGMFs: Powerful test for extra-galactic magnetic fields, very poorly known at the moment… Worth testing!
Typical deflection maps for protons • Larger deflections along the Galactic plane • Typical deflections around 5o • Possible peculiar features in the bulge & halo TT M. Kachelrieß, P.Serpico, M. Teshima Astrop. Phys.26, 378 [astro-ph/0510444] E=4x1019 eV HMR PS
Example of map-distortion by GMF A.C., G. Miele, P.Serpico PLB 660:307-314,2008
Presence of structures • No significant cross-correlation Check with PSCz: cross-correlation Relevant role of magnetic fields Yet the chance probability drops from 50% to 10-15% for the SH model, for x-correlations within 50o No statistical relevance, but reasonable for intermediate-heavy nuclei in the GMF and/or for protons with significant extragalactic deflections. Also, for light nuclei both the auto-correlation and x-correlation are robust with respect to corrections in the GMF (checked 3 models and 3 “effective rigidities”)
CENTAURUS A Radio Sky Chandra: X-ray Jets VLA: Radio Lobes Hubble: Optical Dust Lane
Neutrinos from Cen A A.C., S.Hannestad, arXiv:0712.1830 : ~ 0.4-0.6 events/year Gamma emission: See talk of M.Kachelriess...
Summary Strong hints of LSS anisotropy seen in Pre-Auger data. Correlation with LSS (possibly AGNs) in the Auger data. Possibility of study of Galactic & Extra-Galactic Magnetic fields and single UHECRs sources: UHECR Astronomy Possibility of multimessenger observations of sources with gammas, neutrinos and UHECRs