We report a multi-resolution search for anisotropies in the arrival directions of cosmic rays detected at the Pierre Auger Observatory with local zenith angles up to 80°and energies in excess of 4 EeV (4 × 1018eV). This search is conducted by measuring the angular power spectrum and performing a needlet wavelet analysis in two independent energy ranges. Both analyses are complementary since the angular power spectrum achieves a better performance in identifying large-scale patterns while the needlet wavelet analysis, considering the parameters used in this work, presents a higher efficiency in detecting smaller-scale anisotropies, potentially providing directional information on any observed anisotropies. No deviation from isotropy is observed on any angular scale in the energy range between 4 and 8 EeV. Above 8 EeV, an indication for a dipole moment is captured; while no other deviation from isotropy is observed for moments beyond the dipole one. The corresponding p-values obtained after accounting for searches blindly performed at several angular scales, are 1.3 × 10-5in the case of the angular power spectrum, and 2.5 × 10-3in the case of the needlet analysis. While these results are consistent with previous reports making use of the same data set, they provide extensions of the previous works through the thorough scans of the angular scales.

Multi-resolution anisotropy studies of ultrahigh-energy cosmic rays detected at the Pierre Auger Observatory / A. Aab, P. Abreu, M. Aglietta, I. Al Samarai, I..F..M. Albuquerque, I. Allekotte, A. Almela, J. Alvarez Castillo, J. Alvarez-muã±iz, G..A. Anastasi, L. Anchordoqui, B. Andrada, S. Andringa, C. Aramo, F. Arqueros, N. Arsene, H. Asorey, P. Assis, J. Aublin, G. Avila, A..M. Badescu, A. Balaceanu, R..J. Barreira Luz, C. Baus, J..J. Beatty, K..H. Becker, J..A. Bellido, C. Berat, M..E. Bertaina, X. Bertou, P..L. Biermann, P. Billoir, J. Biteau, S..G. Blaess, A. Blanco, J. Blazek, C. Bleve, M. Bohã¡ä ovã¡, D. Boncioli, C. Bonifazi, N. Borodai, A..M. Botti, J. Brack, I. Brancus, T. Bretz, A. Bridgeman, F..L. Briechle, P. Buchholz, A. Bueno, S. Buitink, M. Buscemi, K..S. Caballero-mora, L. Caccianiga, A. Cancio, F. Canfora, L. Caramete, R. Caruso, A. Castellina, G. Cataldi, L. Cazon, A..G. Chavez, J..A. Chinellato, J. Chudoba, R..W. Clay, R. Colalillo, A. Coleman, L. Collica, M..R. Coluccia, R. Conceiã§ã£o, F. Contreras, M..J. Cooper, S. Coutu, C..E. Covault, J. Cronin, S. D'Amico, B. Daniel, S. Dasso, K. Daumiller, B..R. Dawson, R..M. De Almeida, S..J. De Jong, G..D. Mauro, J..R..T. De Mello Neto, I..D. Mitri, J. De Oliveira, V. De Souza, J. Debatin, O. Deligny, C. Di Giulio, A. Di Matteo, M..L. Dã­az Castro, F. Diogo, C. Dobrigkeit, J..C. D'Olivo, R..C. Dos Anjos, M..T. Dova, A. Dundovic, J. Ebr, R. Engel, M. Erdmann, M. Erfani, C..O. Escobar, J. Espadanal, A. Etchegoyen, H. Falcke, G. Farrar, A..C. Fauth, N. Fazzini, B. Fick, J..M. Figueira, A. Filipä iä , O. Fratu, M..M. Freire, T. Fujii, A. Fuster, R. Gaior, B. Garcã­a, D. Garcia-pinto, F. Gatã©, H. Gemmeke, A. Gherghel-lascu, P..L. Ghia, U. Giaccari, M.G. Giammarchi, M. Giller, D. Gå‚as, C. Glaser, G. Golup, M. Gã³mez Berisso, P..F. Gã³mez Vitale, N. Gonzã¡lez, A. Gorgi, P. Gorham, P. Gouffon, A..F. Grillo, T..D. Grubb, F. Guarino, G..P. Guedes, M..R. Hampel, P. Hansen, D. Harari, T..A. Harrison, J..L. Harton, Q. Hasankiadeh, A. Haungs, T. Hebbeker, D. Heck, P. Heimann, A..E. Herve, G..C. Hill, C. Hojvat, E. Holt, P. Homola, J..R. Hã¶randel, P. Horvath, M. Hrabovskã½, T. Huege, J. Hulsman, A. Insolia, P..G. Isar, I. Jandt, S. Jansen, J..A. Johnsen, M. Josebachuili, A. Kã¤ã¤pã¤, O. Kambeitz, K..H. Kampert, I. Katkov, B. Keilhauer, E. Kemp, J. Kemp, R..M. Kieckhafer, H..O. Klages, M. Kleifges, J. Kleinfeller, R. Krause, N. Krohm, D. Kuempel, G. Kukec Mezek, N. Kunka, A. Kuotb Awad, D. Lahurd, M. Lauscher, R. Legumina, M..A. Leigui De Oliveira, A. Letessier-selvon, I. Lhenry-yvon, K. Link, L. Lopes, R. Lã³pez, A. Lã³pez Casado, Q. Luce, A. Lucero, M. Malacari, M. Mallamaci, D. Mandat, P. Mantsch, A..G. Mariazzi, I..C. Mariåÿ, G. Marsella, D. Martello, H. Martinez, O. Martã­nez Bravo, J..J. Masã­as Meza, H..J. Mathes, S. Mathys, J. Matthews, J..A..J. Matthews, G. Matthiae, E. Mayotte, P..O. Mazur, C. Medina, G. Medina-tanco, D. Melo, A. Menshikov, S. Messina, M..I. Micheletti, L. Middendorf, I..A. Minaya, L. Miramonti, B. Mitrica, D. Mockler, S. Mollerach, F. Montanet, C. Morello, M. Mostafã¡, A..L. Mã¼ller, G. Mã¼ller, M..A. Muller, S. Mã¼ller, R. Mussa, I. Naranjo, L. Nellen, P..H. Nguyen, M. Niculescu-oglinzanu, M. Niechciol, L. Niemietz, T. Niggemann, D. Nitz, D. Nosek, V. Novotny, H. Noå¾ka, L..A. Nãºã±ez, L. Ochilo, F. Oikonomou, A. Olinto, D. Pakk Selmi-dei, M. Palatka, J. Pallotta, P. Papenbreer, G. Parente, A. Parra, T. Paul, M. Pech, F. Pedreira, J. Pkala, R. Pelayo, J. Peã±a-rodriguez, L..A..S. Pereira, M. Perlã­n, L. Perrone, C. Peters, S. Petrera, J. Phuntsok, R. Piegaia, T. Pierog, P. Pieroni, M. Pimenta, V. Pirronello, M. Platino, M. Plum, C. Porowski, R..R. Prado, P. Privitera, M. Prouza, E..J. Quel, S. Querchfeld, S. Quinn, R. Ramos-pollan, J. Rautenberg, D. Ravignani, B. Revenu, J. Ridky, M. Risse, P. Ristori, V. Rizi, W. Rodrigues De Carvalho, G. Rodriguez Fernandez, J. Rodriguez Rojo, D. Rogozin, M..J. Roncoroni, M. Roth, E. Roulet, A..C. Rovero, P. Ruehl, S..J. Saffi, A. Saftoiu, H. Salazar, A. Saleh, F. Salesa Greus, G. Salina, F. Sã¡nchez, P. Sanchez-lucas, E..M. Santos, E. Santos, F. Sarazin, R. Sarmento, C..A. Sarmiento, R. Sato, M. Schauer, V. Scherini, H. Schieler, M. Schimp, D. Schmidt, O. Scholten, P. Schovã¡nek, F..G. Schrã¶der, A. Schulz, J. Schulz, J. Schumacher, S..J. Sciutto, A. Segreto, M. Settimo, A. Shadkam, R..C. Shellard, G. Sigl, G. Silli, O. Sima, A. Åšmiaå‚kowski, R. Å mã­da, G..R. Snow, P. Sommers, S. Sonntag, J. Sorokin, R. Squartini, D. Stanca, S. Staniä , J. Stasielak, P. Stassi, F. Strafella, F. Suarez, M. Suarez Durã¡n, T. Sudholz, T. Suomijã¤rvi, A..D. Supanitsky, J. Swain, Z. Szadkowski, A. Taboada, O..A. Taborda, A. Tapia, V..M. Theodoro, C. Timmermans, C..J. Todero Peixoto, L. Tomankova, B. Tomã©, G. Torralba Elipe, M.D.C. Torri, P. Travnicek, M. Trini, R. Ulrich, M. Unger, M. Urban, J..F. Valdã©s Galicia, I. Valiã±o, L. Valore, G. Van Aar, P. Van Bodegom, A..M. Van Den Berg, A. Van Vliet, E. Varela, B. Vargas Cã¡rdenas, G. Varner, J..R. Vã¡zquez, R..A. Vã¡zquez, D. Veberiä , I..D. Vergara Quispe, V. Verzi, J. Vicha, L. Villaseã±or, S. Vorobiov, H. Wahlberg, O. Wainberg, D. Walz, A..A. Watson, M. Weber, A. Weindl, L. Wiencke, H. Wilczyå„ski, T. Winchen, D. Wittkowski, B. Wundheiler, L. Yang, D. Yelos, A. Yushkov, E. Zas, D. Zavrtanik, M. Zavrtanik, A. Zepeda, B. Zimmermann, M. Ziolkowski, Z. Zong, F. Zuccarello. - In: JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS. - ISSN 1475-7516. - 2017:6(2017), pp. 026.1-026.25. [10.1088/1475-7516/2017/06/026]

Multi-resolution anisotropy studies of ultrahigh-energy cosmic rays detected at the Pierre Auger Observatory

L. Caccianiga;M.G. Giammarchi;M. Mallamaci;L. Miramonti;M.D.C. Torri;
2017

Abstract

We report a multi-resolution search for anisotropies in the arrival directions of cosmic rays detected at the Pierre Auger Observatory with local zenith angles up to 80°and energies in excess of 4 EeV (4 × 1018eV). This search is conducted by measuring the angular power spectrum and performing a needlet wavelet analysis in two independent energy ranges. Both analyses are complementary since the angular power spectrum achieves a better performance in identifying large-scale patterns while the needlet wavelet analysis, considering the parameters used in this work, presents a higher efficiency in detecting smaller-scale anisotropies, potentially providing directional information on any observed anisotropies. No deviation from isotropy is observed on any angular scale in the energy range between 4 and 8 EeV. Above 8 EeV, an indication for a dipole moment is captured; while no other deviation from isotropy is observed for moments beyond the dipole one. The corresponding p-values obtained after accounting for searches blindly performed at several angular scales, are 1.3 × 10-5in the case of the angular power spectrum, and 2.5 × 10-3in the case of the needlet analysis. While these results are consistent with previous reports making use of the same data set, they provide extensions of the previous works through the thorough scans of the angular scales.
Cosmic ray experiments; ultra high energy cosmic rays; Astronomy and Astrophysics
Settore FIS/01 - Fisica Sperimentale
Settore FIS/04 - Fisica Nucleare e Subnucleare
Settore FIS/05 - Astronomia e Astrofisica
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/530220
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