Calculation of the energetic neutral atom flux from a 3D time-dependent model heliosphere

¹ Institut für Experimentelle und Angewandte Physik: Heliosphärische Astroteilchenphysik, Christian-Albrechts-Universität, Leibnizstrasse 11, 24118 Kiel, Germany e-mail: sternal@physik.uni-kiel.de
² Lehrstuhl für Theoretische Physik IV: Theoretische Weltraum- und Astrophysik, Ruhr-Universität Bochum, 44780 Bochum, Germany e-mail: hf@tp4.ruhr-uni-bochum.de

Received: 25 April 2007
Accepted: 18 September 2007

Abstract

With the Interstellar Boundary Explorer (IBEX) the measurement of energetic neutral atoms (ENAs) will enable a remote sensing of the heliospheric boundary region where the solar wind plasma flow meets the interstellar medium. Together with Voyager 1 (& 2) in (and at least near) the healiosheath there will be a very fortunate instrument configuration in space that will allow us to obtain valuable information about the large-scale structure and dynamics of the heliosphere. Following ongoing theoretical discussions we have computed all-sky maps of the differential flux of ENAs produced from charge exchange with solar wind protons in a three-dimensionally structured and time-varying heliosheath. We employ a three-dimensional, time-dependent hydrodynamic model heliosphere to compute the production of ENAs by a generalisation of previous two-dimensional approaches. We find three-dimensionally structured all-sky ENA flux maps that are time-varying due to the solar activity cycle. While the study adds to the complexity of the task to correctly interpret the forthcoming measurements to be made with IBEX, it underlines the potential of this mission to significantly increase our understanding of the structure and dynamics of the heliosphere.