The Impact of Pickup Ion Thermal Spread on Pickup Ion Ring-beam-driven Instabilities and Scattering in the Outer Heliosheath

Mousavi，Ameneh1,2; Liu，Kaijun1; Sadeghzadeh，Sina3

2023-12-01

10.3847/1538-4357/ad05be

Astrophysical Journal   影响因子和分区

0004-637X

1538-4357

The present study investigates the unstable waves driven by the pickup ions of ring-beam distributions with various pickup angles and pickup ion temperatures in the outer heliosheath, using both linear instability analysis and hybrid simulations. While previous papers have generally assumed specific pickup ion temperatures, this study takes a more comprehensive approach by examining a wide range of pickup ion temperatures that may occur in the outer heliosheath. Our one-dimensional simulations demonstrate that regardless of the initial pickup ion temperature, the pitch-angle scattering of the pickup ions at small pickup angles saturates before the pickup ions can reach the hemisphere of negative parallel velocities with respect to the background magnetic field in velocity space, while at a 90° pickup angle, the pickup ions of ring distributions attain a significant level of isotropy. In contrast, the two-dimensional simulation results show that at all pickup angles, increasing the pickup ion temperature only slightly reduces the pickup ion scattering rate, but does not prevent the pickup ions from reaching the hemisphere of negative parallel velocities. Overall, the results do not align with the requirements of the earlier proposed scenarios for the secondary energetic neutral atom (ENA) mechanism of the Interstellar Boundary Explorer ENA ribbon, which demand either weak pickup ion scattering in the outer heliosheath or at least incomplete pickup ion scattering in the off-ribbon directions.

SCI

英语

第一 ; 通讯

WOS:001105688700001

SPACE SCIENCE

2-s2.0-85178188957

Scopus

1.Department of Earth and Space Sciences,Southern University of Science and Technology,Shenzhen,518055,China
2.Center for Space Plasma Physics,Space Science Institute,Boulder,80301,United States
3.Physics and Astronomy Department,Rice University,Houston,77005,United States

Mousavi，Ameneh,Liu，Kaijun,Sadeghzadeh，Sina. The Impact of Pickup Ion Thermal Spread on Pickup Ion Ring-beam-driven Instabilities and Scattering in the Outer Heliosheath[J]. Astrophysical Journal,2023,2(151).

Mousavi，Ameneh,Liu，Kaijun,&Sadeghzadeh，Sina.(2023).The Impact of Pickup Ion Thermal Spread on Pickup Ion Ring-beam-driven Instabilities and Scattering in the Outer Heliosheath.Astrophysical Journal,2(151).

Mousavi，Ameneh,et al."The Impact of Pickup Ion Thermal Spread on Pickup Ion Ring-beam-driven Instabilities and Scattering in the Outer Heliosheath".Astrophysical Journal 2.151(2023).