A New Maximum-Likelihood Technique for Reconstructing Cosmic-Ray Anisotropy at All Angular Scales

Abstract

The arrival directions of TeV-PeV cosmic rays show weak but significant anisotropies with relative intensities at the level of one per mille. Due to the smallness of the anisotropies, quantitative studies require careful disentanglement of detector effects from the observation. We discuss an iterative maximum-likelihood reconstruction that simultaneously fits cosmic ray anisotropies and detector acceptance. The method does not rely on detector simulations and provides an optimal anisotropy reconstruction for ground-based cosmic ray observatories located in the middle latitudes. It is particularly well suited to the recovery of the dipole anisotropy, which is a crucial observable for the study of cosmic ray diffusion in our Galaxy. We also provide general analysis methods for recovering large- and small-scale anisotropies that take into account systematic effects of the observation by ground-based detectors.

version published in The Astrophysical Journal, Volume 823, Number 1

References in corpus (13)

• Anisotropy and Corotation of Galactic Cosmic Rays
• Discovery of Localized Regions of Excess 10-TeV Cosmic Rays
• The Large Scale Cosmic-Ray Anisotropy as Observed with Milagro
• Observation of Cosmic Ray Anisotropy with the IceTop Air Shower Array
• Observation of Small-scale Anisotropy in the Arrival Direction Distribution of TeV Cosmic Rays with HAWC
• ARGO-YBJ Observation of the Large-scale Anisotropy During the Solar Minimum between Cycles 23 and 24
• Solution to the cosmic ray anisotropy problem
• The puzzling MILAGRO hot spots
• Probing Nearby CR Accelerators and ISM Turbulence with Milagro Hot Spots
• The Milagro anticenter hot spots: cosmic rays from the Geminga supernova ?
• Small-Scale Anisotropies of Cosmic Rays from Relative Diffusion
• Magnetic fields and cosmic ray anisotropies at TeV energies
• The Fortuitous Latitude of the Pierre Auger Observatory and Telescope Array for Reconstructing the Quadrupole Moment

Cited by in corpus (14)

• Anisotropy in Cosmic-Ray Arrival Directions in the Southern Hemisphere with Six Years of Data from the IceCube Detector
• Deciphering the Dipole Anisotropy of Galactic Cosmic Rays
• Origin of Small-Scale Anisotropies in Galactic Cosmic Rays
• All-Sky Measurement of the Anisotropy of Cosmic Rays at 10 TeV and Mapping of the Local Interstellar Magnetic Field
• Observation of Anisotropy of TeV Cosmic Rays with Two Years of HAWC
• Search for Very High Energy Gamma Rays from the Northern $\text{Fermi}$ Bubble Region with HAWC
• Neutrinos and Cosmic Rays Observed by IceCube
• Large-Scale Cosmic-Ray Anisotropy as a Probe of Interstellar Turbulence
• TeV Cosmic-Ray Anisotropy from the Magnetic Field at the Heliospheric Boundary
• Measurements and implications of cosmic ray anisotropies from TeV to trans-EeV energies
• Observation of Cosmic-Ray Anisotropy in the Southern Hemisphere with 12 yr of Data Collected by the IceCube Neutrino Observatory
• Large- and Medium-Scale Anisotropies in the Arrival Directions of Cosmic Rays observed with KASCADE-Grande
• Searching for All-Scale Anisotropies in the Arrival Directions of Cosmic Rays above the Ankle
• The Dipole Anisotropy of Galactic Cosmic Rays