Searches for large-scale anisotropy in the arrival directions of cosmic rays detected above energy of 10{sup 19} eV at the Pierre Auger observatory and the telescope array

Journal Article · Mon Oct 20 00:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/794/2/172· OSTI ID:22370374

Aab, A. ^[1]; Abreu, P.; Andringa, S. ^[2]; Aglietta, M. ^[3]; Ahn, E. J. ^[4]; Al Samarai, I. ^[5]; Albuquerque, I. F. M. ^[6]; Allekotte, I.; Asorey, H. ^[7]; Allen, J. ^[8]; Allison, P. ^[9]; Almela, A. ^[10]; Castillo, J. Alvarez ^[11]; Alvarez-Muñiz, J. ^[12]; Batista, R. Alves ^[13]; Ambrosio, M.; Aramo, C. ^[14]; Aminaei, A. ^[15]; Anchordoqui, L. ^[16]; Arqueros, F. ^[17] ; others, and

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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, Orsay (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)
16. University of Wisconsin, Milwaukee, WI (United States)
17. Universidad Complutense de Madrid, Madrid (Spain)

Spherical harmonic moments are well-suited for capturing anisotropy at any scale in the flux of cosmic rays. An unambiguous measurement of the full set of spherical harmonic coefficients requires full-sky coverage. This can be achieved by combining data from observatories located in both the northern and southern hemispheres. To this end, a joint analysis using data recorded at the Telescope Array and the Pierre Auger Observatory above 10{sup 19} eV is presented in this work. The resulting multipolar expansion of the flux of cosmic rays allows us to perform a series of anisotropy searches, and in particular to report on the angular power spectrum of cosmic rays above 10{sup 19} eV. No significant deviation from isotropic expectations is found throughout the analyses performed. Upper limits on the amplitudes of the dipole and quadrupole moments are derived as a function of the direction in the sky, varying between 7% and 13% for the dipole and between 7% and 10% for a symmetric quadrupole.

• OSTI ID: 22370374
• Journal Information: Astrophysical Journal, Vol. 794, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
AMPLITUDES
ANISOTROPY
COSMIC RADIATION
DIPOLES
EXPANSION
QUADRUPOLE MOMENTS
SPECTRA
SPHERICAL CONFIGURATION
SYMMETRY
TELESCOPES