Relating Energetic Ion Spectra to Energetic Neutral Atoms

Abstract Heliospheric energetic neutral atoms (ENAs) originate from ions that are neutralized by charge exchange with in the heliosheath and very local interstellar medium (VLISM). Since unaffected electromagnetic fields, they propagate ballistically same speeds as parent particles. Consequently, measurements of ENA distributions allow one to remotely image ion VLISM. The origin spawn ENAs is still debated, particularly at energies higher than ∼keV. In this work, we summarize five possible sources cover energy a few keV hundreds keV. Three related pickup (PUIs): those PUIs transmitted across heliospheric termination shock (HTS), reflected once or multiple times HTS, i.e., PUIs, multiply further accelerated HTS. Two other kinds can be considered suprathermal tail PUI distribution particles By way illustration, use these particle distributions, taking account their evolution heliosheath, calculate intensities analyze characteristics spectra observed 1 au.