Spectral Properties of ENAs in the Presence of Multiple PUI Populations.

The flux of energetic neutral atoms (ENAs) seen in the heliotail direction by the IBEX spacecraft shows a powerlaw-like dependence on energy in the 0.5 to 6 keV range. Given that the thermal core of the heliosheath plasma has been measured by Voyager 2 to be a few 100,000 K, which is likely similar to the thermal core temperature at other locations, these ENAs must come from a suprathermal population of protons, known as pick-up ions (PUIs). We have developed a model for heliosheath PUIs based on multiple Maxwellians that in aggregate conform to the (collisionless) MHD equations. In this poster we explore a range of parameters for this model to see how the global energetics of the plasma may be subdivided into different populations of PUIs that represent the parent population of the ENAs observed by IBEX. By matching the model line of sight spectrum with the data, we can determine the likely breakdown of these populations, which has implications for the way in which they are energized by the termination shock (TS).