Indication of anisotropy in arrival directions of ultra-high-energy cosmic rays through comparison to the flux pattern of extragalactic gamma-ray sources
Creators: name: The Pierre Auger Collaboration
name: Aab, A.
name: Abreu, P.
name: Aglietta, M.
name: Albuquerque, I. F. M.
name: Allekotte, I.
name: Almela, A.
name: Castillo, J. Alvarez
name: Alvarez-Muñiz, J.
name: Anastasi, G. A.
name: Anchordoqui, L.
name: Andrada, B.
name: Andringa, S.
name: Aramo, C.
name: Arsene, N.
name: Asorey, H.
name: Assis, P.
name: Avila, G.
name: Badescu, A. M.
name: Balaceanu, A.
name: Barbato, F.
name: Luz, R. J. Barreira
name: Beatty, J. J.
name: Becker, K. H.
name: Bellido, J. A.
name: Berat, C.
name: Bertaina, M. E.
name: Bertou, X.
name: Biermann, P. L.
name: Biteau, J.
name: Blaess, S. G.
name: Blanco, A.
name: Blazek, J.
name: Bleve, C.
name: Boháčová, M.
name: Bonifazi, C.
name: Borodai, N.
name: Botti, A. M.
name: Brack, J.
name: Brancus, I.
name: Bretz, T.
name: Bridgeman, A.
name: Briechle, F. L.
name: Buchholz, P.
name: Bueno, A.
name: Buitink, S.
name: Buscemi, M.
name: Caballero-Mora, K. S.
name: Caccianiga, L.
name: Cancio, A.
name: Canfora, F.
name: Caruso, R.
name: Castellina, A.
name: Catalani, F.
name: Cataldi, G.
name: Cazon, L.
name: Chavez, A. G.
name: Chinellato, J. A.
name: Chudoba, J.
name: Clay, R. W.
name: Cerutti, A. C. Cobos
name: Colalillo, R.
name: Coleman, A.
name: Collica, L.
name: Coluccia, M. R.
name: Conceição, R.
name: Consolati, G.
name: Contreras, F.
name: Cooper, M. J.
name: Coutu, S.
name: Covault, C. E.
name: Cronin, J.
name: D'Amico, S.
name: Daniel, B.
name: Dasso, S.
name: Daumiller, K.
name: Dawson, B. R.
name: de Almeida, R. M.
name: de Jong, S. J.
name: De Mauro, G.
name: Neto, J. R. T. de Mello
name: De Mitri, I.
name: de Oliveira, J.
name: de Souza, V.
name: Debatin, J.
name: Deligny, O.
name: Castro, M. L. Díaz
name: Diogo, F.
name: Dobrigkeit, C.
name: D'Olivo, J. C.
name: Dorosti, Q.
name: Anjos, R. C. dos
name: Dova, M. T.
name: Dundovic, A.
name: Ebr, J.
name: Engel, R.
name: Erdmann, M.
name: Erfani, M.
name: Escobar, C. O.
name: Espadanal, J.
name: Etchegoyen, A.
name: Falcke, H.
name: Farmer, J.
name: Farrar, G.
name: Fauth, A. C.
name: Fazzini, N.
name: Fenu, F.
name: Fick, B.
name: Figueira, J. M.
name: Filipčič, A.
name: Freire, M. M.
name: Fujii, T.
name: Fuster, A.
name: Gaïor, R.
name: García, B.
name: Gaté, F.
name: Gemmeke, H.
name: Gherghel-Lascu, A.
name: Ghia, P. L.
name: Giaccari, U.
name: Giammarchi, M.
name: Giller, M.
name: Głas, D.
name: Glaser, C.
name: Golup, G.
name: Berisso, M. Gómez
name: Vitale, P. F. Gómez
name: González, N.
name: Gorgi, A.
name: Grillo, A. F.
name: Grubb, T. D.
name: Guarino, F.
name: Guedes, G. P.
name: Halliday, R.
name: Hampel, M. R.
name: Hansen, P.
name: Harari, D.
name: Harrison, T. A.
name: Haungs, A.
name: Hebbeker, T.
name: Heck, D.
name: Heimann, P.
name: Herve, A. E.
name: Hill, G. C.
name: Hojvat, C.
name: Holt, E.
name: Homola, P.
name: Hörandel, J. R.
name: Horvath, P.
name: Hrabovský, M.
name: Huege, T.
name: Hulsman, J.
name: Insolia, A.
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name: Jandt, I.
name: Johnsen, J. A.
name: Josebachuili, M.
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name: Kääpä, A.
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name: Kampert, K. H.
name: Keilhauer, B.
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name: Kemp, E.
name: Kemp, J.
name: Kieckhafer, R. M.
name: Klages, H. O.
name: Kleifges, M.
name: Kleinfeller, J.
name: Krause, R.
name: Krohm, N.
name: Kuempel, D.
name: Mezek, G. Kukec
name: Kunka, N.
name: Awad, A. Kuotb
name: Lago, B. L.
name: LaHurd, D.
name: Lang, R. G.
name: Lauscher, M.
name: Legumina, R.
name: de Oliveira, M. A. Leigui
name: Letessier-Selvon, A.
name: Lhenry-Yvon, I.
name: Link, K.
name: Presti, D. Lo
name: Lopes, L.
name: López, R.
name: Casado, A. López
name: Lorek, R.
name: Luce, Q.
name: Lucero, A.
name: Malacari, M.
name: Mallamaci, M.
name: Mandat, D.
name: Mantsch, P.
name: Mariazzi, A. G.
name: Mariş, I. C.
name: Marsella, G.
name: Martello, D.
name: Martinez, H.
name: Bravo, O. Martínez
name: Meza, J. J. Masías
name: Mathes, H. J.
name: Mathys, S.
name: Matthews, J.
name: Matthiae, G.
name: Mayotte, E.
name: Mazur, P. O.
name: Medina, C.
name: Medina-Tanco, G.
name: Melo, D.
name: Menshikov, A.
name: Merenda, K. -D.
name: Michal, S.
name: Micheletti, M. I.
name: Middendorf, L.
name: Miramonti, L.
name: Mitrica, B.
name: Mockler, D.
name: Mollerach, S.
name: Montanet, F.
name: Morello, C.
name: Morlino, G.
name: Mostafá, M.
name: Müller, A. L.
name: Müller, G.
name: Muller, M. A.
name: Müller, S.
name: Mussa, R.
name: Naranjo, I.
name: Nellen, L.
name: Nguyen, P. H.
name: Niculescu-Oglinzanu, M.
name: Niechciol, M.
name: Niemietz, L.
name: Niggemann, T.
name: Nitz, D.
name: Nosek, D.
name: Novotny, V.
name: Nožka, L.
name: Núñez, L. A.
name: Oikonomou, F.
name: Olinto, A.
name: Palatka, M.
name: Pallotta, J.
name: Papenbreer, P.
name: Parente, G.
name: Parra, A.
name: Paul, T.
name: Pech, M.
name: Pedreira, F.
name: Pękala, J.
name: Pelayo, R.
name: Peña-Rodriguez, J.
name: Pereira, L. A. S.
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name: Phuntsok, J.
name: Pierog, T.
name: Pimenta, M.
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name: Platino, M.
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name: Porowski, C.
name: Prado, R. R.
name: Privitera, P.
name: Prouza, M.
name: Quel, E. J.
name: Querchfeld, S.
name: Quinn, S.
name: Ramos-Pollan, R.
name: Rautenberg, J.
name: Ravignani, D.
name: Ridky, J.
name: Riehn, F.
name: Risse, M.
name: Ristori, P.
name: Rizi, V.
name: de Carvalho, W. Rodrigues
name: Fernandez, G. Rodriguez
name: Rojo, J. Rodriguez
name: Roncoroni, M. J.
name: Roth, M.
name: Roulet, E.
name: Rovero, A. C.
name: Ruehl, P.
name: Saffi, S. J.
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name: Sánchez, F.
name: Sanchez-Lucas, P.
name: Santos, E. M.
name: Santos, E.
name: Sarazin, F.
name: Sarmento, R.
name: Sarmiento-Cano, C.
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name: Schauer, M.
name: Scherini, V.
name: Schieler, H.
name: Schimp, M.
name: Schmidt, D.
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name: Schröder, S.
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name: Taborda, O. A.
name: Theodoro, V. M.
name: Timmermans, C.
name: Peixoto, C. J. Todero
name: Tomankova, L.
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name: Elipe, G. Torralba
name: Travnicek, P.
name: Trini, M.
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name: Unger, M.
name: Urban, M.
name: Galicia, J. F. Valdés
name: Valiño, I.
name: Valore, L.
name: van Aar, G.
name: van Bodegom, P.
name: Berg, A. M. van den
name: van Vliet, A.
name: Varela, E.
name: Cárdenas, B. Vargas
name: Vázquez, R. A.
name: Veberič, D.
name: Ventura, C.
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name: Verzi, V.
name: Vicha, J.
name: Villaseñor, L.
name: Vorobiov, S.
name: Wahlberg, H.
name: Wainberg, O.
name: Walz, D.
name: Watson, A. A.
name: Weber, M.
name: Weindl, A.
name: Wiedeński, M.
name: Wiencke, L.
name: Wilczyński, H.
name: Wirtz, M.
name: Wittkowski, D.
name: Wundheiler, B.
name: Yang, L.
name: Yushkov, A.
name: Zas, E.
name: Zavrtanik, D.
name: Zavrtanik, M.
name: Zepeda, A.
name: Zimmermann, B.
name: Ziolkowski, M.
name: Zong, Z.
name: Zuccarello, F.
Publisher: name: arXiv
Year: 2018
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: A new analysis of the dataset from the Pierre Auger Observatory provides evidence for anisotropy in the arrival directions of ultra-high-energy cosmic rays on an intermediate angular scale, which is indicative of excess arrivals from strong, nearby sources. The data consist of 5514 events above 20 EeV with zenith angles up to 80 deg recorded before 2017 April 30. Sky models have been created for two distinct populations of extragalactic gamma-ray emitters: active galactic nuclei from the second catalog of hard Fermi-LAT sources (2FHL) and starburst galaxies from a sample that was examined with Fermi-LAT. Flux-limited samples, which include all types of galaxies from the Swift-BAT and 2MASS surveys, have been investigated for comparison. The sky model of cosmic-ray density constructed using each catalog has two free parameters, the fraction of events correlating with astrophysical objects and an angular scale characterizing the clustering of cosmic rays around extragalactic sources. A maximum-likelihood ratio test is used to evaluate the best values of these parameters and to quantify the strength of each model by contrast with isotropy. It is found that the starburst model fits the data better than the hypothesis of isotropy with a statistical significance of 4.0 sigma, the highest value of the test statistic being for energies above 39 EeV. The three alternative models are favored against isotropy with 2.7-3.2 sigma significance. The origin of the indicated deviation from isotropy is examined and prospects for more sensitive future studies are discussed.
description: Published version, 10 pages, 3 figures, 2 tables