Speaker
Prof.
Jacek Niemiec
(Institute of Nuclear Physics PAN, Krakow, Poland)
Description
The nearly circular band of energetic neutral atom (ENA) emission dominating the
field of view of the Interplanetary Boundary EXplorer satellite (IBEX), is most
commonly attributed to the effect of charge exchange of secondary pickup ions
(PUIs) gyrating about the magnetic field in the outer heliosheath and the
interstellar space beyond.
The main difficulty with this model is the problem with stability of ring distributions that tend to generate waves and scatter onto a shell on time scales too short for charge exchange to occur. We performed a careful study of the ring instability using theoretical dispersion relations, hybrid plasma simulations, and fully kinetic PIC
simulations that included electron dynamics.
In addition to several prescribed distributions, we used primary ENA fluxes from
the global kinetic-neutral model of the heliosphere to obtain a smooth empirical representation of the PUI ring produced from solar-wind and heliosheath ENAs. Simulations reveal that the ring distribution generates both left- and right-hand polarized waves traveling parallel to the background magnetic field. Narrow rings generate abundant magnetic fluctuations at the resonant frequencies, whereas simulations with broadened rings show very low levels of turbulence. Nonetheless, particle scattering occurs for every type of rings we studied. Results are discussed in the context of IBEX observations of the ribbon and the recent Voyager 1 in situ measurements of magnetic field fluctuations in the outer heliosheath.
| Registration number following "ICRC2015-I/" | 357 |
|---|---|
| Collaboration | -- not specified -- |
Primary author
Prof.
Jacek Niemiec
(Institute of Nuclear Physics PAN, Krakow, Poland)
Co-authors
Prof.
Jacob Heerikhuisen
(Department of Physics, University of Alabama, Huntsville, AL, USA)
Dr
Ken-Ichi Nishikawa
(Department of Physics, University of Alabama, Huntsville, AL, USA)
Prof.
Vladimir Florinski
(Department of Physics, University of Alabama, Huntsville, AL, USA)
