Searches for anisotropies in the arrival directions of the highest energy cosmic rays detected by the Pierre Auger Observatory

Journal Article · Fri May 01 00:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/804/1/15· OSTI ID:22883257

Aab, A. ^[1]; Abreu, P. ^[2]; Aglietta, M. ^[3]; Ahn, E. J. ^[4]; Samarai, I. Al ^[5]; Albuquerque, I. F. M. ^[6]; Allekotte, I. ^[7]; Allen, J. ^[8]; Allison, P. ^[9]; Almela, A. ^[10]; Castillo, J. Alvarez ^[11]; Alvarez-Muñiz, J. ^[12]; Batista, R. Alves ^[13]; Ambrosio, M. ^[14]; Aminaei, A. ^[15]; others, and

---

1. Universität Siegen, Siegen (Germany)
2. Laboratório de Instrumentação e Física Experimental de Partículas—LIP and Instituto Superior Técnico—IST, Universidade de Lisboa—UL (Portugal)
3. Osservatorio Astrofisico di Torino (INAF), Università di Torino and Sezione INFN, Torino (Italy)
4. Fermilab, Batavia, IL (United States)
5. Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris 11, CNRS-IN2P3 (France)
6. Universidade de São Paulo, Instituto de Física, São Paulo, SP (Brazil)
7. Centro Atómico Bariloche and Instituto Balseiro (CNEA-UNCuyo-CONICET), San Carlos de Bariloche (Argentina)
8. New York University, New York, NY (United States)
9. Ohio State University, Columbus, OH (United States)
10. Universidad Tecnológica Nacional—Facultad Regional Buenos Aires, Buenos Aires (Argentina)
11. Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)
12. Universidad de Santiago de Compostela (Spain)
13. Universität Hamburg, Hamburg (Germany)
14. Università di Napoli “Federico II” and Sezione INFN, Napoli (Italy)
15. IMAPP, Radboud University Nijmegen (Netherlands)

We analyze the distribution of arrival directions of ultra-high-energy cosmic rays recorded at the Pierre Auger Observatory in 10 years of operation. The data set, about three times larger than that used in earlier studies, includes arrival directions with zenith angles up to 80°, thus covering from −90{sup ∘} to +45{sup ∘} in declination. After updating the fraction of events correlating with the active galactic nuclei (AGNs) in the Véron-Cetty and Véron catalog, we subject the arrival directions of the data with energies in excess of 40 EeV to different tests for anisotropy. We search for localized excess fluxes, self-clustering of event directions at angular scales up to 30°, and different threshold energies between 40 and 80 EeV. We then look for correlations of cosmic rays with celestial structures both in the Galaxy (the Galactic Center and Galactic Plane) and in the local universe (the Super-Galactic Plane). We also examine their correlation with different populations of nearby extragalactic objects: galaxies in the 2MRS catalog, AGNs detected by Swift-BAT, radio galaxies with jets, and the Centaurus A (Cen A) galaxy. None of the tests show statistically significant evidence of anisotropy. The strongest departures from isotropy (post-trial probability ∼1.4%) are obtained for cosmic rays with E>58 EeV in rather large windows around Swift AGNs closer than 130 Mpc and brighter than 10{sup 44} erg s{sup −1} (18° radius), and around the direction of Cen A (15° radius).

• OSTI ID: 22883257
• Journal Information: Astrophysical Journal, Vol. 804, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ANISOTROPY
CATALOGS
COSMIC RADIATION
DISTRIBUTION
GALAXY NUCLEI
GAMMA DETECTION
RADIO GALAXIES
THRESHOLD ENERGY
UNIVERSE