Implications of solar wind suprathermal tails for IBEX ENA images of the heliosheath

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Read Full Article (file size: 283357 bytes) Cited by JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, A06102, doi:10.1029/2007JA012758, 2008 Implications of solar wind suprathermal tails for IBEX ENA images of the heliosheath C. Prested Department of Astronomy, Center for Space Physics and Center for Integrated Space Weather Modeling, Boston University, Boston, Massachusetts, USA N. Schwadron Department of Astronomy, Center for Space Physics and Center for Integrated Space Weather Modeling, Boston University, Boston, Massachusetts, USA J. Passuite Department of Astronomy, Center for Space Physics and Center for Integrated Space Weather Modeling, Boston University, Boston, Massachusetts, USA B. Randol Department of Astronomy, Center for Space Physics and Center for Integrated Space Weather Modeling, Boston University, Boston, Massachusetts, USA Space Science and Engineering Division, Southwest Research Institute, San Antonio, Texas, USA B. Stuart Department of Astronomy, Center for Space Physics and Center for Integrated Space Weather Modeling, Boston University, Boston, Massachusetts, USA Institute for Astronomy, University of Hawaii, Honolulu, Hawaii, USA G. Crew Department of Astronomy, Center for Space Physics and Center for Integrated Space Weather Modeling, Boston University, Boston, Massachusetts, USA Kavli Institute for Astrophysics and Space Research, Massachusetts Institute for Technology, Cambridge, Massachusetts, USA J. Heerikhuisen Institute of Geophysics and Planetary Physics, University of California, Riverside, California, USA N. Pogorelov Institute of Geophysics and Planetary Physics, University of California, Riverside, California, USA G. Zank Institute of Geophysics and Planetary Physics, University of California, Riverside, California, USA M. Opher Department of Physics and Astronomy, George Mason University, Fairfax, Virginia, USA F. Allegrini Space Science and Engineering Division, Southwest Research Institute, San Antonio, Texas, USA D. J. McComas Space Science and Engineering Division, Southwest Research Institute, San Antonio, Texas, USA M. Reno Space Science and Engineering Division, Southwest Research Institute, San Antonio, Texas, USA E. Roelof Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, USA S. Fuselier Space Physics Laboratory, Lockheed Martin, Palo Alto, California, USA H. Funsten Los Alamos National Laboratory, Los Alamos, New Mexico, USA E. Moebius Space Science Center and Department of Physics, University of New Hampshire, Durham, New Hampshire, USA L. Saul Physikalisches Institut, Space and Planetary Sciences, University of Bern, Bern, Switzerland Abstract Decades of interplanetary measurements of the solar wind and other space plasmas have established that the suprathermal ion intensity distributions (j) are non-Maxwellian and are characterized by high-energy power law tails (j ∼ E⁻). Recent analysis by Fisk and Gloeckler of suprathermal ion observations between 1–5 AU demonstrates that a particular differential intensity distribution function emerges universally between ∼2–10 times the solar wind speed with ∼ 1.5. This power law tail is particularly apparent in downstream distributions beyond reverse shocks associated with corotating interaction regions. Similar power law tails have been observed in the downstream flow beyond the termination shock by the Low Energy Charged Particle instrument on both Voyager 1 and Voyager 2. Using kappa distributions with internal energy, density, and bulk flow derived from large-scale magnetohydrodynamic models, we calculate the simulated flux of energetic neutral atoms (ENAs) produced in the heliosheath by charge exchange between solar wind protons and interstellar hydrogen. We then produce simulated ENA maps of the heliosheath, such as will be measured by the Interstellar Boundary Explorer Mission (IBEX). We also estimate the expected signal to noise and background ratio for IBEX. The solar wind suprathermal tail significantly increases the ENA flux within the IBEX energy range, ∼0.01–6 keV, by more than an order of magnitude at the highest energies over the estimates using a Maxwellian. It is therefore essential to consider suprathermal tails in the interpretation of IBEX ENA images and theoretical modeling of the heliospheric termination shock. Received 24 August 2007; accepted 25 February 2008; published 12 June 2008. Index Terms: 2124 Interplanetary Physics: Heliopause and solar wind termination; 2126 Interplanetary Physics: Heliosphere/interstellar medium interactions; 2151 Interplanetary Physics: Neutral particles (7837); 2114 Interplanetary Physics: Energetic particles (7514); 2164 Interplanetary Physics: Solar wind plasma. Read Full Article (file size: 283357 bytes) Cited by Citation: Prested, C., et al. (2008), Implications of solar wind suprathermal tails for IBEX ENA images of the heliosheath, J. Geophys. Res., 113, A06102, doi:10.1029/2007JA012758. Copyright 2008 by the American Geophysical Union.

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