Statistical methods for partitioning ribbon and globally-distributed flux using data from the Interstellar Boundary Explorer

TL;DR

This paper introduces statistical techniques to decompose ENA flux maps from IBEX into ribbon and globally-distributed sources, enabling better understanding of the heliosphere boundary and interstellar magnetic field.

Contribution

The paper presents novel statistical methods for source separation in ENA flux maps, with improved flexibility and uncertainty estimation over previous approaches.

Findings

Effective separation of ribbon and global flux sources demonstrated on simulated data.

New method for estimating the ribbon center aids in studying interstellar magnetic field.

Enhanced uncertainty quantification improves reliability of flux source estimates.

Abstract

ASA's Interstellar Boundary Explorer (IBEX) satellite collects data on energetic neutral atoms (ENAs) that can provide insight into the heliosphere boundary between our solar system and interstellar space. Using these data, scientists can construct maps of the ENA intensities (often, expressed in terms of flux) observed in all directions. The ENA flux observed in these maps is believed to come from at least two distinct sources: one source which manifests as a ribbon of concentrated ENA flux and one source (or possibly several) that manifest as smoothly-varying globally-distributed flux. Each ENA source type and its corresponding ENA intensity map is of separate scientific interest. In this paper, we develop statistical methods for separating the total ENA intensity maps into two source-specific maps (ribbon and globally-distributed flux) and estimating corresponding uncertainty. Key advantages of the proposed method include enhanced model flexibility and improved propagation of estimation uncertainty. We evaluate the proposed methods on simulated data designed to mimic realistic data settings. We also propose new methods for estimating the center of the near-elliptical ribbon in the sky, which can be used in the future to study the location and variation of the local interstellar magnetic field.