The Re-Acceleration of Galactic Electrons at the Heliospheric Termination Shock

Observations by the Voyager spacecraft in the outer heliosphere presented several challenges for the paradigm of diffusive shock acceleration (DSA) at the solar wind termination shock (TS). In this study, the viability of DSA as a re-acceleration mechanism for galactic electrons is investigated usin...

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Bibliographic Details
Published in:The Astrophysical journal 2017-02, Vol.836 (1), p.100
Main Authors: Prinsloo, P. L., Potgieter, M. S., Strauss, R. D.
Format: Article
Language:English
Subjects:
ACCELERATION
acceleration of particles
Astrophysics
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COMPARATIVE EVALUATIONS
COSMIC RADIATION
Cosmic ray modulation
Cosmic rays
EFFICIENCY
ELECTRON SPECTRA
ELECTRONS
Galactic electrons
HELIOSPHERE
Interstellar
MODULATION
SIMULATION
SOLAR WIND
Spacecraft
SUN
Sun: heliosphere
Viability
VOYAGER SPACE PROBES
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Summary:Observations by the Voyager spacecraft in the outer heliosphere presented several challenges for the paradigm of diffusive shock acceleration (DSA) at the solar wind termination shock (TS). In this study, the viability of DSA as a re-acceleration mechanism for galactic electrons is investigated using a comprehensive cosmic-ray modulation model. The results demonstrate that the efficiency of DSA depends strongly on the shape of the electron spectra incident at the TS, which in turn depends on the features of the local interstellar spectrum. Modulation processes such as drifts therefore also influence the re-acceleration process. It is found that re-accelerated electrons make appreciable contributions to intensities in the heliosphere and that increases caused by DSA at the TS are comparable to intensity enhancements observed by Voyager 1 ahead of the TS crossing. The modeling results are interpreted as support for DSA as a re-acceleration mechanism for galactic electrons at the TS.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/836/1/100