  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.
