Title

Observation of small-scale anisotropy in the arrival direction distribution of TeV cosmic rays with HAWC

Authors

A. U. Abeysekara, Michigan State University
R. Alfaro, Universidad Nacional Autónoma de México
C. Alvarez, Universidad Autónoma de Chiapas
J. D. Álvarez, Universidad Michoacana de San Nicolás de Hidalgo
R. Arceo, Universidad Autónoma de Chiapas
J. C. Arteaga-Velázquez, Universidad Michoacana de San Nicolás de Hidalgo
H. A.Ayala Solares, Michigan Technological University
A. S. Barber, The University of Utah
B. M. Baughman, University of Maryland
N. Bautista-Elivar, Universidad Politécnica de Pachuca
E. Belmont, Universidad Nacional Autónoma de México
S. Y. BenZvi, University of Rochester
D. Berley, University of Maryland
M. Bonilla Rosales, Instituto Nacional de Astrofisica Optica y Electronica
J. Braun, University of Maryland
K. S. Caballero-Mora, Centro de Investigacion y de Estudios Avanzados
A. Carramiñana, Instituto Nacional de Astrofisica Optica y Electronica
M. Castillo, Benemerita Universidad Autonoma de Puebla
U. Cotti, Universidad Michoacana de San Nicolás de Hidalgo
J. Cotzomi, Benemerita Universidad Autonoma de Puebla
E. De La Fuente, Universidad de Guadalajara
C. De Léon, Universidad Michoacana de San Nicolás de Hidalgo
T. DeYoung, Michigan State University
R. Diaz Hernandez, Instituto Nacional de Astrofisica Optica y Electronica
J. C. Díaz-Vélez, University of Wisconsin-Madison
B. L. Dingus, Los Alamos National Laboratory
M. A. DuVernois, University of Wisconsin-Madison
R. W. Ellsworth, University of Maryland
D. W. Fiorino, University of Wisconsin-Madison
N. Fraija, Universidad Nacional Autónoma de México
A. Galindo, Instituto Nacional de Astrofisica Optica y Electronica
F. Garfias, Universidad Nacional Autónoma de México

Document Type

Article

Publication Date

12-1-2014

Abstract

© 2014. The American Astronomical Society. All rights reserved. Printed in the U.S.A. The High-Altitude Water Cherenkov (HAWC) Observatory is sensitive to gamma rays and charged cosmic rays at TeV energies. The detector is still under construction, but data acquisition with the partially deployed detector started in 2013. An analysis of the cosmic-ray arrival direction distribution based on 4.9 × 1010 events recorded between 2013 June and 2014 February shows anisotropy at the 10-4 level on angular scales of about 10°. The HAWC cosmic-ray sky map exhibits three regions of significantly enhanced cosmic-ray flux; two of these regions were first reported by the Milagro experiment. A third region coincides with an excess recently reported by the ARGO-YBJ experiment. An angular power spectrum analysis of the sky shows that all terms up to l = 15 contribute significantly to the excesses.

Publication Title

Astrophysical Journal

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