Observation of Small-scale Anisotropy in the Arrival Direction Distribution of TeV Cosmic Rays with HAWC

Abstract

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 $4.9\times 10^{10}$ events recorded between June 2013 and February 2014 shows anisotropy at the $10^{-4}$ level on angular scales of about $10^{\circ }$. 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 $\ell =15$ contribute significantly to the excesses.

12 pages, 11 figures. Accepted by The Astrophysical Journal

References in corpus (5)

• Discovery of Localized Regions of Excess 10-TeV Cosmic Rays
• The Large Scale Cosmic-Ray Anisotropy as Observed with Milagro
• Measurement of the Anisotropy of Cosmic Ray Arrival Directions with IceCube
• Evolution of the cosmic ray anisotropy above 10^{14} eV
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Cited by in corpus (12)

• Radio detection of Cosmic-Ray Air Showers and High-Energy Neutrinos
• ARGO-YBJ Observation of the Large-scale Anisotropy During the Solar Minimum between Cycles 23 and 24
• All-Sky Measurement of the Anisotropy of Cosmic Rays at 10 TeV and Mapping of the Local Interstellar Magnetic Field
• Progress in high-energy cosmic ray physics
• Ultralight Black Holes as Sources of High-Energy Particles
• Angular Power Spectra with Finite Counts
• An Isotropy Measurement with Gravitational Wave Observations
• Statistically study the optimal local sources for cosmic ray nuclei and electron
• Understanding the phase reversals of Galactic cosmic ray anisotropies
• Comic ray flux anisotropies caused by astrospheres
• Cherenkov telescope array extragalactic survey discovery potential and the impact of axion-like particles and secondary gamma rays
• Detection of Cosmic Rays from ground: an Introduction