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Title: A NEW MODEL FOR THE HELIOSPHERE’S “IBEX RIBBON”

We present a model for the narrow, ribbon-like enhancement in the emission of ∼keV energetic neutral atoms (ENA) coming from the outer heliosphere, coinciding roughly with the plane of the very local interstellar magnetic field (LISMF). We show that the pre-existing turbulent LISMF has sufficient amplitude in magnitude fluctuations to efficiently trap ions with initial pitch-angles near 90°, primarily by magnetic mirroring, leading to a narrow region of enhanced pickup-proton intensity. The pickup protons interact with cold interstellar hydrogen to produce ENAs seen at 1 AU. The computed width of the resulting ribbon of emission is consistent with observations. We also present results from a numerical model that are also generally consistent with the observations. Our interpretation relies only on the pre-existing turbulent interstellar magnetic field to trap the pickup protons. This leads to a broader local pitch-angle distribution compared to that of a ring. Our numerical model also predicts that the ribbon is double-peaked with a central depression. This is a further consequence of the (primarily) magnetic mirroring of pickup ions with pitch-angles close to 90° in the pre-existing, turbulent interstellar magnetic field.
Authors:
;  [1]
  1. Department of Planetary Sciences, University of Arizona, Tucson, AZ (United States)
Publication Date:
OSTI Identifier:
22518848
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 812; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ATOMS; COMPARATIVE EVALUATIONS; COSMIC PROTONS; DIFFUSION; FLUCTUATIONS; HELIOSPHERE; HYDROGEN; INCLINATION; INTERSTELLAR MAGNETIC FIELDS; MAGNETIC MIRRORS; SUN; TURBULENCE