Separation of the interstellar boundary explorer ribbon from globally distributed energetic neutral atom flux

N. A. Schwadron, F. Allegrini, M. Bzowski, E. R. Christian, G. B. Crew, M. Dayeh, R. Demajistre, P. Frisch, H. O. Funsten, S. A. Fuselier, K. Goodrich, M. Gruntman, P. Janzen, H. Kucharek, G. Livadiotis, D. J. McComas, E. Moebius, C. Prested, D. Reisenfeld, M. RenoE. Roelof, J. Siegel, R. Vanderspek

Research output: Contribution to journalArticle

110 Scopus citations

Abstract

The Interstellar Boundary Explorer (IBEX) observes a remarkable feature, the IBEX ribbon, which has energetic neutral atom (ENA) flux over a narrow region ∼20° wide, a factor of 2-3 higher than the more globally distributed ENA flux. Here, we separate ENA emissions in the ribbon from the distributed flux by applying a transparency mask over the ribbon and regions of high emissions, and then solve for the distributed flux using an interpolation scheme. Our analysis shows that the energy spectrum and spatial distribution of the ribbon are distinct from the surrounding globally distributed flux. The ribbon energy spectrum shows a knee between ∼1 and 4keV, and the angular distribution is approximately independent of energy. In contrast, the distributed flux does not show a clear knee and more closely conforms to a power law over much of the sky. Consistent with previous analyses, the slope of the power law steepens from the nose to tail, suggesting a weaker termination shock toward the tail as compared to the nose. The knee in the energy spectrum of the ribbon suggests that its source plasma population is generated via a distinct physical process. Both the slope in the energy distribution of the distributed flux and the knee in the energy distribution of the ribbon are ordered by latitude. The heliotail may be identified in maps of globally distributed flux as a broad region of low flux centered ∼44°W of the interstellar downwind direction, suggesting heliotail deflection by the interstellar magnetic field.

Original languageEnglish (US)
Article number56
JournalAstrophysical Journal
Volume731
Issue number1
DOIs
StatePublished - Apr 10 2011
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • ISM: general
  • Sun: heliosphere
  • magnetohydrodynamics (MHD)
  • plasmas
  • shock waves
  • solar wind

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    Schwadron, N. A., Allegrini, F., Bzowski, M., Christian, E. R., Crew, G. B., Dayeh, M., Demajistre, R., Frisch, P., Funsten, H. O., Fuselier, S. A., Goodrich, K., Gruntman, M., Janzen, P., Kucharek, H., Livadiotis, G., McComas, D. J., Moebius, E., Prested, C., Reisenfeld, D., ... Vanderspek, R. (2011). Separation of the interstellar boundary explorer ribbon from globally distributed energetic neutral atom flux. Astrophysical Journal, 731(1), [56]. https://doi.org/10.1088/0004-637X/731/1/56