Kinetic vs. multi-fluid approach for interstellar neutrals in the heliosphere: exploration of the interstellar magnetic field effects

TL;DR

This paper introduces a new 3D self-consistent model combining MHD and kinetic approaches to study the interaction between the solar wind and interstellar medium, highlighting the importance of kinetic modeling of neutral hydrogen.

Contribution

The paper presents a novel kinetic-MHD model for the solar wind and interstellar neutrals, improving upon previous multi-fluid models by capturing key heliospheric features.

Findings

Decreased heliocentric distance to the termination shock

Thinner heliosheath observed with kinetic model

Reduced flow deflection angle in the heliosheath

Abstract

We present a new 3d self-consistent two-component (plasma and neutral hydrogen) model of the solar wind interaction with the local interstellar medium (LISM). This model (K-MHD) combines the MHD treatment of the solar wind and the ionized LISM component, with a kinetic model of neutral interstellar hydrogen (LISH). The local interstellar magnetic field (BLISM) intensity and orientation are chosen based on an early analysis of the heliosheath flows (Opher et al. 2009). The properties of the plasma and neutrals obtained using the (K-MHD) model are compared to previous multi-fluid (Opher et al. 2009) and kinetic models (Izmodenov et al. 2005). The new treatment of LISH revealed important changes in the heliospheric properties not captures by the multi-fluid model. These include a decrease in the heliocentric distance to the termination shock (TS), a thinner heliosheath and a reduced deflection angle ({\theta}) of the heliosheath flows. The asymmetry of the termination shock, however, seems to be unchanged by the kinetic aspect of the LISH.