HR: 0800h
AN: SH51A-1191    [Abstracts]
TI: Where is the Anomalous Cosmic Ray Accelerator and Why did Voyager Miss It?
AU: * Schwadron, N A
EM: nathanas@bu.edu
AF: Boston University, Dept of Astronomy, 725 Commonwealth, Boston, MA 02215 United States
AU: McComas, D J
EM: dmccomas@swri.edu
AF: Southwest Research Institute, 6220 Culebra, San Antonio, TX 78238-5166 United States
AB: Voyager recently passed beyond the termination shock, but did not see the expected unfolding of the Anomalous Cosmic Ray (ACR) spectrum. There are three possibilities for ACR acceleration implied by these Voyager observations: (1) it occurs at the termination shock, but at locations other than that passed through by Voyager, (2) it occurred at the location crossed by Voyager, but at some previous time, or (3) it occurs beyond the termination shock. In this presentation we will explore the possibility that ACRs are produced at Favored Acceleration Locations on the Termination Shock (FALTS), where either the shock structure or the magnetic field is configured to provide enhanced acceleration. We will also explore the possibility that the termination shock is not the dominant cosmic ray accelerator, and instead, anomalous cosmic rays are accelerated beyond it through stochastic acceleration. Both cases represent significant departures from traditional views about anomalous cosmic ray acceleration at the termination shock. We explore these possibilities using a new energetic particle model, Energetic Particle Seed Solver (EPSeedS), that numerically solves the fully time, space, and energy dependent Boltzmann transport equations for particle distributions uniform in hemispheres separated by 90 degree pitch-angle. Our model has significant advantages over more traditional models that have difficulty accurately modeling energetic particles at low energies where diffusion techniques break down. EPSeedS therefore solves energetic particle distributions from the suprathermal and pickup ion seed populations to their energetic particle and anomalous cosmic ray products. We compare Voyager observations with predicted distributions from Favored Acceleration Locations at the Termination Shock (FALTS), and stochastic acceleration beyond it to search for where and how ACRs are accelerated.
DE: 2104 Cosmic rays
DE: 2109 Discontinuities (7811)
DE: 2124 Heliopause and solar wind termination
DE: 2126 Heliosphere/interstellar medium interactions
DE: 2152 Pickup ions
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005