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The footprint of large scale cosmic structure on the UHECRs (and gamma) distribution

The footprint of large scale cosmic structure on the UHECRs (and gamma) distribution. Cuoco A, D’Abrusco R, Longo G, Miele G and Serpico P D, 2006 JCAP. 0601:009. Alessandro Cuoco, Università degli studi di Napoli Federico II. Otranto September 1 0 2006. Sky Distribution.

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The footprint of large scale cosmic structure on the UHECRs (and gamma) distribution

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  1. The footprint of large scale cosmicstructure on the UHECRs (and gamma) distribution Cuoco A, D’Abrusco R, Longo G, Miele G and Serpico P D, 2006 JCAP. 0601:009 Alessandro Cuoco, Università degli studi di Napoli Federico II Otranto September 1 0 2006

  2. 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?)…

  3. Energy Spectrum (2) Cosmic-ray spectrum  E2.7 The spectrum is a Piecewise Power Law: E-γ= 2.7- 3.0- 2.8 Clearly visible the Knee at E=1015 eV and the Ankle at E=5x1018 eV The change in slope is generally due to a change in composition and/or a change in astrophysical origin or in the acceleration mechanism… Unsolved problem…

  4. Pierre Auger Observatory 3000 Km2 surface • Auger observatory will • use hybrid techniques reducing considerably the sistematics… Southern hemisphere: Malargüe Provincia de Mendoza Argentina • Statistics of events • of about 50-100 UHECRs with E>4x1019 eV per year

  5. Large Scale Structures (LSS) SDSS mesurements have confirmed the results of numerical (hydrodynamical) simulation: Universe has a foam-like Structure rich of voids and filaments along which the galaxies are aligned; The structures start to be homogeneous and isotropic by about 100 Mpc and are visible till the farest explored regions at about 1Gpc SDSS Galaxies and Structures 1Gpc

  6. Local Universe (200 Mpc) 2MASS Survey

  7. Local Universe (Eq. Coordinates)

  8. Redshift informations

  9. IRAS PSCz Survey Mask and sky distribution of the PSCz sources Redshift distribution and selection function • Worst quality respect to 2MASS: • About 15.000 Gal. in PSCz against 1.5 millions of • 2MASS, and less sky coverage, but easier to manage • Better quality in redshifts: spectroscopic • redshifts available with negligible errors • For 2MASS only photometry is available from which • photometric redshifts are calculable only with • great errors (tipically 20-30%)

  10. Propagation of particles Photopion Production Cosmological Redshift Mpc Bhete-Heitler Pair Production : P + γCMB p + e+e- Combined effect Energy Loss 10 EeV z Energy Loss and Interaction Length (dE/dz)/Efor a proton injected at z=0.2 and Energy=100 EeV. Interaction Length not always constant, expecially for photopion production due to the tight dependence of cross section on energy: exponential weight and attenuation not truly valid

  11. Model prediction Can we test the hypothesis that the UHECRs come from local sources (the GZK sphere)? • Some assumption is needed: • Sources are numerous and follow the • distribution of LSS • GZK is true (quite a consequence…) • Standard propagation and particles (protons) • Magnetic fields not very strong • (rectilinear propagation) Propagation Resulting UHECRs flux integrated from a lower threshold of 5x1019 eV

  12. Energy Cut Dependence Ecut=30 EeV Ecut=50 EeV Ecut=70 EeV Ecut=90 EeV Equal area Hammer–Aitoff projections of the smoothed UHECR arrival directions distribution in galactic coordinates obtained for fixed s = 2.0 and Ecut = 3, 5, 7, 9 × 1019 eV. The smoothing angle is σ = 3◦. The contours enclose 95%, 68%, 38%, 20% of the corresponding distribution.

  13. Method How many events to detect the anisotropies? Comparison cell by cell with a pure uniform distribution random generated with 2 statistics:

  14. Forecast predictions 200 events 2 distribution obtained from 10.000 Montecarlo simulations 400 events Comparison of LSS model and isotropic model distributions Distributions normalized to Unit Area About 600 events required to distinguish structures from an isotropic background 600 events AUGER proper sky coverage and exposure included: 600 events about 4-5 years of AUGER 800 events Alternatives: top-down, Strong magnetic fields, Point sources… Reduced 2:r2

  15. Power Spectrum Non gaussian features: Power spectrum contains only part of the full map information! Strong dipole and quadrupole anisotropy!

  16. Magnetic Fields Map of deflection angles from the local clusters Cumulative distribution of deflection angles From G.Sigl In some cases strong deflections up to 50 degrees seems possible making particle astronomy not possible, but intergalactic magnetic fields are very poor known… Worth testing!

  17. Gamma Analogy Gamma Horizon E-z Plane Critical (=1) contour : Optical Depth Attenuation = Exp(-) • Photon interactions at TeV energy give a gamma horizon of the same order size of GZK horizon • The main interaction is: γγe+e- • pair production with e+e- cascading Stecker et al. astro-ph/0510449

  18. MAGIC(Germany, Spain, Italy)Summer 20031 telescope 17 meters Ø VERITAS(USA & England)2005?7 telescopes10 meters Ø Montosa Canyon, Arizona Roque delos Muchachos, Canary Islands CANGAROO III(Australia & Japan)Spring 20044 telescopes 10 meters Ø Windhoek, Namibia HESS(Germany & France)Summer 20024 (16) telescopes 12 meters Ø Woomera, Australia Satellite and Ground based gamma ray astronomy Air Shower Cerenkov telescopes Energy Range > 50 GeV GLAST: to be launched in 2007 Energy Range 10 MeV-500 GeV

  19. Ground Based Surveys Wide-angle instruments surveying ~ 2-3  “Threshold” Sens. (1 y) Milagro ~ 2 TeV ~ 0.5 Crab Tibet III shower array ~ 3 TeV ~ 1 Crab ARGO YBJ 0.5 – 1 TeV ~ 0.5 Crab Crab signal Tibet array Milagro ARGO

  20. Milagro Galactic Plane Preliminary Significance • GP diffuse excess clearly visible from l=25° to l=90° • Cygnus Region at l=65°-85° and |b|<3° shows extended excess • FCygnus ~ 2 x Fcrab From B.Dingus, Elba06

  21. TeV Gamma Sky TeV Gamma Sky From Large Scale Structures Cuoco A, Hannestad S, Haugbølle T, Miele G, Serpico PD & Tu H In Progress… TeV angular Power Spectra Halo Model N-body Simulation

  22. Summary and Conclusions • In a standard scenario of composition (protons) and propagation of • UHECRs GZK limits the sources to beno far than 100 Mpc (the GZK • sphere) • Anisotropies in the arrival distribution and flux of the UHECRs is • expected to correlate with the local cosmological structures • All sky astronomical surveys (2MASS, IRAS) and propagation codes can • be used to construct a realistic model of the expected flux anisotropy • Statistical analysis indicates order few hundreds events are required to • distinguish the structures from isotropic background, corresponding to • 4-5 years of AUGER • Given enough statistics the model can be confirmed or ruled out: in both • cases valuable conclusion: beginning of UHECRs astronomy in first case • or confirmation of non standard feature in the second: strong magnetic • fields, atypical sources, exotic particles and propagation…

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