TY - JOUR
T1 - Determining the IBEX Ribbon Transverse Profile from ENA Temporal Variations
T2 - A Proof of Concept for IMAP Observations
AU - Dayeh, M. A.
AU - Zirnstein, E. J.
AU - McComas, D. J.
N1 - Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/3/1
Y1 - 2023/3/1
N2 - Since its discovery in 2009, the IBEX energetic neutral atom (ENA) Ribbon has been a subject of numerous studies. It appears at energies ∼0.5-6 keV and is most pronounced at ∼1-3 keV. It is almost circular, ∼20°-40° wide, and its center lies near the pristine local interstellar magnetic field direction, whose field lines are draped around the heliosphere. The Ribbon intensity is enhanced above the more diffuse, globally distributed flux (GDF) and varies on timescales that are delayed compared to the underlying and slowly varying GDF. We present a novel method to infer the Ribbon boundaries and transverse profile of the Ribbon using sequential time variations of ENA fluxes, with minimal modeling assumptions involved. The method utilizes the difference in temporal evolution between the total Ribbon content and GDF fluxes. We then use the inferred Ribbon transverse profile to statistically quantify the GDF contribution to the observed peak Ribbon intensity to be ∼32.23% ± 3.15% in 2009-2011. This Ribbon separation method works best during times of gradual changes in solar wind output, and with high angular resolution and ENA counting statistics; results thus provide a proof of concept for the upcoming Interstellar Mapping and Acceleration Probe ENA measurements.
AB - Since its discovery in 2009, the IBEX energetic neutral atom (ENA) Ribbon has been a subject of numerous studies. It appears at energies ∼0.5-6 keV and is most pronounced at ∼1-3 keV. It is almost circular, ∼20°-40° wide, and its center lies near the pristine local interstellar magnetic field direction, whose field lines are draped around the heliosphere. The Ribbon intensity is enhanced above the more diffuse, globally distributed flux (GDF) and varies on timescales that are delayed compared to the underlying and slowly varying GDF. We present a novel method to infer the Ribbon boundaries and transverse profile of the Ribbon using sequential time variations of ENA fluxes, with minimal modeling assumptions involved. The method utilizes the difference in temporal evolution between the total Ribbon content and GDF fluxes. We then use the inferred Ribbon transverse profile to statistically quantify the GDF contribution to the observed peak Ribbon intensity to be ∼32.23% ± 3.15% in 2009-2011. This Ribbon separation method works best during times of gradual changes in solar wind output, and with high angular resolution and ENA counting statistics; results thus provide a proof of concept for the upcoming Interstellar Mapping and Acceleration Probe ENA measurements.
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U2 - 10.3847/2041-8213/acbe00
DO - 10.3847/2041-8213/acbe00
M3 - Article
AN - SCOPUS:85150410908
SN - 2041-8205
VL - 945
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L33
ER -