Galactic Cosmic Rays in the Outer Heliosphere The

Authors: V Florinski S E S Ferreira N V Pogorelov

Publish Date: 2011/03/03

Volume: 176, Issue: 1-4, Pages: 147-163

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Abstract

We review recent advances in the field of galactic cosmic ray transport in the distant heliosphere The advent of global MHD models brought about a better understanding of the threedimensional structure of the interface between the solar system and the surrounding interstellar space and of the magnetic field topology in the outer heliosphere These results stimulated a development of galactic cosmic ray transport models taking the advantage of the available detailed plasma backgrounds and of the new Voyager results from the heliosheath It emerges that the heliosheath plays a prominent role in the process of modulation and filtration of lowenergy galactic ions and electrons The heliosheath stores particles for a duration of several years thus acting as a large reservoir of galactic cosmic rays Cosmicray trajectories transit times and entry locations across the heliopause are discussedWhen compared to observations model calculations of low energy electrons show almost no radial gradient up to the termination shock irrespective of solar activity but a large gradient in the inner heliosheath Intensities are however sensitive to heliospheric conditions such as the location of the heliopause and shock In contrast high energy proton observations by both the Voyager spacecraft show a clear solar cycle dependence with intensities also increasing with increasing distance By comparing these observations to model calculations we can establish whether our current understanding of longterm modulation result in computed intensities compatible to observations

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