Search for anisotropies in cosmic-ray positrons detected by the PAMELA experiment

Abstract

The PAMELA detector was launched on board of the Russian Resurs-DK1 satellite on June 15, 2006. Data collected during the first four years have been used to search for large-scale anisotropies in the arrival directions of cosmic-ray positrons. The PAMELA experiment allows for a full sky investigation, with sensitivity to global anisotropies in any angular window of the celestial sphere. Data samples of positrons in the rigidity range 10 GV $\le$ R $\le$ 200 GV were analyzed. This article discusses the method and the results of the search for possible local sources through analysis of anisotropy in positron data compared to the proton background. The resulting distributions of arrival directions are found to be isotropic. Starting from the angular power spectrum, a dipole anisotropy upper limit δ= 0.166 at 95% C.L. is determined. Additional search is carried out around the Sun. No evidence of an excess correlated with that direction was found.

The value of the dipole anisotropy upper limit has been changed. The method is correct but there was a miscalculation in the relative formula

References in corpus (10)

• Observation of an anomalous positron abundance in the cosmic radiation
• PAMELA - A Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics
• The cosmic-ray electron flux measured by the PAMELA experiment between 1 and 625 GeV
• Anisotropy and Corotation of Galactic Cosmic Rays
• Galactic secondary positron flux at the Earth
• 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
• A Cosmic Ray Positron Anisotropy due to Two Middle-Aged, Nearby Pulsars?
• Implications of the Cosmic Ray Electron Spectrum and Anisotropy measured with Fermi-LAT

Cited by in corpus (7)

• WIMP dark matter candidates and searches - current status and future prospects
• Dipole anisotropy in cosmic electrons and positrons: inspection on local sources
• Status of Indirect (and Direct) Dark Matter searches
• Dark matter indirect signals with long-lived mediators
• Snowmass 2021 LoI: Determination of cosmic ray properties in the local interstellar medium with all-sky anisotropy observations
• Probing the astrophysical origin of high-energy cosmic-ray electrons with Monte Carlo simulation
• Anisotropies in GeV-TeV cosmic ray electrons and positrons