Authors: Ethan Schuyler Bair (Boston University), Merav Opher (Boston University), Bart van der Holst (Boston University), Marc Zachary Kornbleuth (Boston University), Gary Zank (University of Alabama in Huntsville), Vladimir Florinski (University of Alabama in Huntville)

Pickup ions (PUIs) dominate the thermal pressure beyond about 10 au from the sun, making them critical to understanding the structure and dynamics of the outer heliosphere.  Global models of the heliosphere often neglect PUIs, and recent global models that have included them typically only consider PUIs created in the supersonic solar wind and assume they follow a Maxwellian distribution. These models showed that PUIs remove energy from the plasma when they charge exchange, leading to an overall thinning of the heliosheath. However, the assumption that PUIs follow a Maxwellian distribution is inconsistent with New Horizons measurements, and the PUI velocity distribution needs to be modeled more accurately.  Here we present the first global heliosphere model to self-consistently treat the full distribution of PUIs up to 200 keV. Instead of modeling the PUIs as a Maxwellian fluid, we treat them as an isotropic velocity distribution.  At the termination shock, the plasma is compressed and heated adiabatically, shifting PUIs to higher energies and creating a high energy tail. We model this tail, which can potentially remove even more energy from the plasma when experiencing charge exchange, further thinning the heliosheath. In addition to the adiabatic heating from compression, PUIs may also experience non-adiabatic heating, which needs to be constrained. We also consider low energy PUIs created in the heliosheath, which become the dominant ion population as the plasma moves toward the tail.  We explore the consequences of the PUIs for the heliosheath plasma and its global structure.