Oblique Electromagnetic Instabilities Driven by Pickup Ion Ring-beam Distributions in the Outer Heliosheath. II. Hybrid Simulations

Mousavi, Ameneh; Liu, Kaijun; Sadeghzadeh, Sina

2022-11-01

10.3847/1538-4357/ac9a43

ASTROPHYSICAL JOURNAL   Impact Factor & Quartile

0004-637X

1538-4357

Hybrid simulations are carried out to study the instabilities driven by the outer heliosheath pickup ions of ring-beam velocity distributions. Following the linear instability analysis in the companion paper, the electromagnetic instabilities at various propagation directions (0 degrees <= theta <= 180 degrees) are studied for pickup ion ring-beam distributions of different pickup angles (0 degrees <= alpha <= 90 degrees). Previous studies of the ring-beam pickup ion distributions have been limited to the parallel- and antiparallel-propagating modes (theta = 0 degrees and 180 degrees). In this paper, several one-dimensional hybrid simulations are performed to investigate the most unstable modes of different propagation angles predicted by the linear instability analysis. Moreover, two-dimensional hybrid simulations are conducted to examine the simultaneous excitation of the parallel, antiparallel, and oblique unstable modes and their role in the scattering of the outer heliosheath pickup ions. Our recent one-dimensional hybrid and particle-in-cell simulations with simulation domains along the background magnetic field demonstrated that at small pickup angles, the outer heliosheath pickup ions experience an incomplete scattering limited to the hemisphere of positive parallel velocities with respect to the background magnetic field. In contrast, the present two-dimensional hybrid simulation results show that when both parallel/antiparallel and oblique unstable modes are acting together, the pickup ions can be scattered into the hemisphere of negative parallel velocities and approach a near-isotropic velocity distribution. This is in conflict with the spatial retention scenario of the energetic neutral atom ribbon observed by the Interstellar Boundary Explorer, which requires pickup ions at small pickup angles to stream away from the ribbon directions.

SCI

English

First ; Corresponding

Strategic Priority Research Program of Chinese Academy of Sciences[XDB 41000000] ; National Natural Science Foundation of China (NSFC)["41974168","42174203"] ; Shenzhen Science and Technology Program["JCYJ20190809153407516","JCY20210324104810027"]

Astronomy & Astrophysics

Astronomy & Astrophysics

WOS:000886671200001

IOP Publishing Ltd

SPACE SCIENCE

Web of Science

Southern Univ Sci & Technol, Dept Earth & Space Sci, Shenzhen 518055, Peoples R China

Mousavi, Ameneh,Liu, Kaijun,Sadeghzadeh, Sina. Oblique Electromagnetic Instabilities Driven by Pickup Ion Ring-beam Distributions in the Outer Heliosheath. II. Hybrid Simulations[J]. ASTROPHYSICAL JOURNAL,2022,940(1):37.

Mousavi, Ameneh,Liu, Kaijun,&Sadeghzadeh, Sina.(2022).Oblique Electromagnetic Instabilities Driven by Pickup Ion Ring-beam Distributions in the Outer Heliosheath. II. Hybrid Simulations.ASTROPHYSICAL JOURNAL,940(1),37.

Mousavi, Ameneh,et al."Oblique Electromagnetic Instabilities Driven by Pickup Ion Ring-beam Distributions in the Outer Heliosheath. II. Hybrid Simulations".ASTROPHYSICAL JOURNAL 940.1(2022):37.