Comic ray flux anisotropies caused by astrospheres

TL;DR

This paper models how astrospheres or stellar wind bubbles act as small-scale sinks affecting cosmic ray flux, potentially explaining observed anisotropies in TeV energies.

Contribution

It introduces a 2D model of astrospheres as cosmic ray sinks and quantifies their impact on flux anisotropies at Earth.

Findings

Small-scale sinks can cause flux decreases of a few permille.

Model results align with observed anisotropies by IceCube and Milagro.

Astrospheres influence cosmic ray propagation at TeV energies.

Abstract

Huge astrospheres or stellar wind bubbles influence the propagation of cosmic rays at energies up to the TeV range and can act as small-scale sinks decreasing the cosmic ray flux. We model such a sink (in 2D) by a sphere of radius 10\,pc embedded within a sphere of a radius of 1\,kpc. The cosmic ray flux is calculated by means of backward stochastic differential equations from an observer, which is located at $r_{0}$, to the outer boundary. It turns out that such small-scale sinks can influence the cosmic ray flux at the observer's location by a few permille (i.e\ a few 0.1\%), which is in the range of the observations by IceCube, Milagro and other large area telescopes.