A. Aab, Radboud Universiteit
P. Abreu, Instituto Superior Técnico
M. Aglietta, Istituto Nazionale di Fisica Nucleare, Sezione di Torino
I. F.M. Albuquerque, Universidade de São Paulo
J. M. Albury, The University of Adelaide
I. Allekotte, Centro Atomico Bariloche
A. Almela, Universidad Nacional de San Martín
J. Alvarez Castillo, Universidad Nacional Autónoma de México
J. Alvarez-Muiz, Universidad de Santiago de Compostela
G. A. Anastasi, Istituto Nazionale di Fisica Nucleare, Sezione di Torino
L. Anchordoqui, Lehman College
B. Andrada, Universidad Nacional de San Martín
S. Andringa, Instituto Superior Técnico
C. Aramo, Istituto Nazionale di Fisica Nucleare, Sezione di Napoli
P. R.Araújo Ferreira, Rheinisch-Westfälische Technische Hochschule Aachen
H. Asorey, Universidad Nacional de San Martín
P. Assis, Instituto Superior Técnico
G. Avila, Pierre Auger Observatory
A. M. Badescu, University Politehnica of Bucharest
A. Bakalova, Institute of Physics of the Czech Academy of Sciences
A. Balaceanu, Horia Hulubei National Institute of Physics and Nuclear Engineering
F. Barbato, Istituto Nazionale di Fisica Nucleare, Sezione di Napoli
R. J.Barreira Luz, Instituto Superior Técnico
K. H. Becker, Bergische Universität Wuppertal
J. A. Bellido, The University of Adelaide
C. Berat, Universite Grenoble Alpes
M. E. Bertaina, Istituto Nazionale di Fisica Nucleare, Sezione di Torino
X. Bertou, Centro Atomico Bariloche
P. L. Biermann, Max Planck Institute for Radio Astronomy
T. Bister, Rheinisch-Westfälische Technische Hochschule Aachen
J. Biteau, Institut de Physique Nucléaire d’Orsay
A. Blanco, Instituto Superior Técnico
J. Blazek, Institute of Physics of the Czech Academy of Sciences
C. Bleve, University Grenoble Alpes
M. Boháčová, Institute of Physics of the Czech Academy of Sciences
D. Boncioli, INFN Laboratori Nazionali del Gran Sasso
C. Bonifazi, Universidade Federal do Rio de Janeiro
L. Bonneau Arbeletche, Universidade de Sao Paulo
N. Borodai, Institute of Nuclear Physics PAN, Krakow, Poland
A. M. Botti, Instiuto de Tecnologias en Deteccion y Astroparticulas
J. Brack, Colorado State University - Fort Collins
T. Bretz, RWTH Aachen University
F. L. Briechle, RWTH Aachen University
P. Buchholz, Universitat Siegen
A. Bueno, Universidad de Granada and C.A.F.P.E.
S. Buitink, Vrije Universiteit Brussel
M. Buscemi, Sezione di Catania
K. S. Caballero-Mora, Universidad Autonoma de Chiapas
L. Caccianiga, Universita di Milano - Bicocca
L. Calcagni, Universidad Nacional de La Plata
A. Cancio, Instituto de Tecnologias en Deteccion y Astroparticulas
F. Canfora, Radboud University Nijmegen
I. Caracas, Bergische Universitat Wuppertal
J. M. Carceller, Uniersidad de Granada and C.A.F.P.E.
R. Caruso, Sezione di Catania
A. Castellina, Sezione di Torino
F. Catalani, Universidade de Sao Paulo
G. Cataldi, Sezione di Lecce
L. Cazon, Universidade de Lisboa
M. Cerda, Observatorio Pierre Auger
J. A. Chinellato, Universidade Estadual de Campinas
K. Choi, Universite Libre de Bruxelles
J. Chudoba, Institute of Physics of the Czech Academy of Sciences
L. Chytka, Palacky University
R. W. Clay, University of Adelaide
A. C. Cobos Cerutti, nstituto de Tecnologías en Detección y Astropartículas
R. Colalillo, Sezione di Napoli
A. Coleman, University of Delaware
M. R. Coluccia, Sezione di Lecce
R. Coneicao, Universidade de Lisboa

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We present measurements of the large-scale cosmic-ray (CR) anisotropies in R.A., using data collected by the surface detector array of the Pierre Auger Observatory over more than 14 yr. We determine the equatorial dipole component, through a Fourier analysis in R.A. that includes weights for each event so as to account for the main detector-induced systematic effects. For the energies at which the trigger efficiency of the array is small, the "east-west" method is employed. Besides using the data from the array with detectors separated by 1500 m, we also include data from the smaller but denser subarray of detectors with 750 m separation, which allows us to extend the analysis down to ∼0.03 EeV. The most significant equatorial dipole amplitude obtained is that in the cumulative bin above 8 EeV, %, which is inconsistent with isotropy at the 6σ level. In the bins below 8 EeV, we obtain 99% CL upper bounds on d ⊥ at the level of 1%-3%. At energies below 1 EeV, even though the amplitudes are not significant, the phases determined in most of the bins are not far from the R.A. of the Galactic center, at GC =-94°, suggesting a predominantly Galactic origin for anisotropies at these energies. The reconstructed dipole phases in the energy bins above 4 EeV point instead to R.A. that are almost opposite to the Galactic center one, indicative of an extragalactic CR origin.

Publication Source (Journal or Book title)

Astrophysical Journal