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dc.contributor.authorArmstrong, Craig Keith
dc.contributor.authorLitvinenko, Yuri E.
dc.contributor.authorCraig, Ian J.D.
dc.identifier.citationArmstrong, C. K., Litvinenko, Y. E., & Craig, I. J. D. (2012). Modeling focused acceleration of cosmic-ray particles by stochastic methods. The Astrophysical Journal, 757(2), Published online.en_NZ
dc.description.abstractSchlickeiser & Shalchi suggested that a first-order Fermi mechanism of focused particle acceleration could be important in several astrophysical applications. In order to investigate focused acceleration, we express the Fokker-Planck equation as an equivalent system of stochastic differential equations. We simplify the system for a set of physically motivated parameters, extend the analytical theory, and determine the evolving particle distribution numerically. While our numerical results agree with the focused acceleration rate of Schlickeiser & Shalchi for a weakly anisotropic particle distribution, we establish significant limitations of the analytical approach. Momentum diffusion is found to be more significant than focused acceleration at early times. Most critically, the particle distribution rapidly becomes anisotropic, leading to a much slower momentum gain rate. We discuss the consequences of our results for the role of focused acceleration in astrophysics.en_NZ
dc.publisherInstitute of Physics -IOPen_NZ
dc.relation.ispartofThe Astrophysical Journal
dc.subjectacceleration of particlesen_NZ
dc.subjectcosmic raysen_NZ
dc.titleModeling focused acceleration of cosmic-ray particles by stochastic methodsen_NZ
dc.typeJournal Articleen_NZ
dc.relation.isPartOfThe Astrophysical Journalen_NZ
uow.identifier.article-noARTN 165en_NZ

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