THE IBEX RIBBON AND THE PICKUP ION RING STABILITY IN THE OUTER HELIOSHEATH. II. MONTE-CARLO AND PARTICLE-IN-CELL MODEL RESULTS

Journal Article · Mon Aug 01 00:00:00 EDT 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/826/2/198· OSTI ID:22679582

Niemiec, J. ^[1]; Florinski, V.; Heerikhuisen, J. ^[2]

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1. Institute of Nuclear Physics PAN, Radzikowskiego 152 31-342 Krakow (Poland)
2. Department of Space Science and Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

The nearly circular ribbon of energetic neutral atom (ENA) emission discovered by NASA’s 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 (OHS) and the interstellar space beyond. The first paper in the series (Paper I) presented a theoretical analysis of the pickup process in the OHS and hybrid-kinetic simulations, revealing that the kinetic properties of freshly injected proton rings depend sensitively on the details of their velocity distribution. It was demonstrated that only rings that are not too narrow (parallel thermal spread above a few km s{sup −1}) and not too wide (parallel temperature smaller than the core plasma temperature) could remain stable for a period of time long enough to generate ribbon ENAs. This paper investigates the role of electron dynamics and the extra spatial degree of freedom in the ring ion scattering process with the help of two-dimensional full particle-in-cell (PIC) kinetic simulations. A good agreement is observed between ring evolution under unstable conditions in hybrid and PIC models, and the dominant modes are found to propagate parallel to the magnetic field. We also present more realistic ribbon PUI distributions generated using Monte Carlo simulations of atomic hydrogen in the global heliosphere and examine the effect of both the cold ring-like and the hot “halo” PUIs produced from heliosheath ENAs on the ring stability. It is shown that the second PUI population enhances the fluctuation growth rate, leading to faster isotropization of the solar-wind-derived ring ions.

• OSTI ID: 22679582
• Journal Information: Astrophysical Journal, Vol. 826, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
COMPUTERIZED SIMULATION
DISTRIBUTION
ELECTRON TEMPERATURE
EXPLORER SATELLITES
FLUCTUATIONS
HELIOSPHERE
HYBRIDIZATION
HYDROGEN
INTERSTELLAR SPACE
ION RINGS
ION TEMPERATURE
MAGNETIC FIELDS
MONTE CARLO METHOD
NASA
PLASMA
PROTONS
SOLAR WIND
TURBULENCE
TWO-DIMENSIONAL CALCULATIONS
VELOCITY