Entity: Architecture-agnostic General Coordinate (QED)(GR)PIC Code for Simulating Astrophysical Plasmas*

Over the past decade, particle-in-cell (PIC) has become the preferred method for simulating plasma physics in the vicinity of compact astrophysical objects. However, there is currently no publicly available code that encompasses all the necessary radiation-plasma coupling processes and can effectively model large-scale systems. In this presentation, I will introduce Entity, a state-of-the-art open-source PIC code specifically designed for extreme astrophysical plasmas. Built upon the Kokkos framework, Entity boasts efficient implicit multi-architecture portability, including GPU utilization. Notably, the code incorporates advanced algorithms to handle diverse radiation-plasma coupling phenomena, such as Compton scattering, electron-positron pair production, and annihilation. Entity is constructed within a general coordinate system defined by metric functions, enabling it to successfully tackle global models of compact object magnetospheres. These models necessitate algorithms operating on non-cartesian grids (e.g., spherical, cubed-sphere) with varying densities, and even encompassing full general relativity. To enhance usability, Entity is packaged with a runtime GUI based on OpenGL for real-time data visualization and a Python-based post-processing framework.