The Role of the Heliosphere in Shaping the Observed Cosmic Ray Spectral Anisotropy

TL;DR

This study investigates how the heliosphere influences the observed anisotropy in cosmic ray spectra at TeV energies, using advanced modeling to connect heliospheric magnetic effects with experimental anisotropy features.

Contribution

It is the first to incorporate detailed heliosphere magnetic field effects into cosmic ray trajectory simulations to explain spectral anisotropy observations.

Findings

Identified a region with a harder cosmic ray spectrum matching observations.

Demonstrated the heliosphere's magnetic field significantly affects cosmic ray spectral features.

Connected heliospheric effects with observed spectral anisotropy in the sky.

Abstract

Experimental results by Milagro, HAWC, and ARGO-YBJ have observed variations in the energy spectrum of cosmic rays at TeV scales in different regions of the sky. These findings on the spectral anisotropy provide insights into cosmic ray behavior. This work explores the impact of galactic cosmic ray interactions with the heliosphere in creating the observed spectral anisotropy features. Specifically, the features around 1-10 TeV, where our previous studies on the heliosphere have shown the greatest effects. In this project, we integrate particle trajectories in a state-of-the-art MHD-kinetic heliosphere model that includes the effects of the solar cycle and interaction with the interstellar medium's magnetic field. With these elements, this is the first time the exact effects of the heliosphere's magnetic field are tested to determine their influence on galactic cosmic rays and their spectral anisotropy. In our results, we identified an area on the map that exhibits a distinct cosmic ray energy spectrum compared to the all-sky distribution. This area approximately coincides with Region A, where observations have found a harder energy spectrum than the isotropic spectrum.