Author ORCID Identifier

https://orcid.org/0009-0007-0108-2318

Date of Award

Spring 5-12-2026

Document Type

Thesis (Ph.D.)

Department or Program

Physics and Astronomy

First Advisor

Hans Mueller

Abstract

As interstellar neutral hydrogen (ISN H) is the most abundant neutral element in the helio- sphere, the region within which the solar wind interacts with the portion of the interstellar medium through which our solar system moves through, it is integral that we aim to under- stand its many properties and interactions within this region. This work details the synthesis and use of a model of ISN H, using trajectory methods to backtrace from a target point at a radial distance of 1 au where explorer probes like Interstellar Boundary Explorer (IBEX) and Interstellar Mapping and Acceleration Probe (IMAP) reside. Over the course of the thesis, I build the model from the ground up using various components of the radiation pres- sure force that influences ISN H trajectories alongside solar gravity, ionization processes that cause neutral losses on the journey from boundary surfaces from 70 to 100 au from the Sun, and boundary conditions on the phase space density both drawn from a global heliosphere model and from analytic formulas used in recent literature. Each step details the notable dy- namical results from this first principles model and records any interesting findings that are not well-discussed in literature, such as the phenomenon of pseudo-bound orbits, as well as making occasional comparisons of simulation results to other published results. Ultimately, I make comparisons of simulation results using the fully realized model with distributions of ISN H intensity calculated directly from the IBEX-Lo instrument. The comparisons result in total summed intensities for both sets of boundary distributions that are on the same order of magnitude as that resulting from the calculated IBEX-Lo data (all on the order of ∼ 106 cm-2 s-1 sr-2). Results also show a trend of overestimated simulated intensity peaks earlier in the season centered around ∼ −125o heliolongitude in ecliptic coordinates on the equator, with underestimated peaks at the core of the calculated data intensity distribution centered around ∼ −105o heliolongitude, also on the equator.

Download

Share

COinS