Zitao Hu, Xue-Ning Bai, Xiaochen Sun
Abstract We present the formulation, algorithm, and numerical tests of the magnetohydrodynamic particle-in-cell (MHD-PIC) method with particles treated under the guiding center approximation, which we term the MHD-gPIC method, and it is implemented in the Athena++ MHD code. The new MHD-gPIC model consists of thermal (cold) fluid and high-energy particles whose dynamics are integrated through guiding center equations including drift motion, with carefully evaluated source terms as particle back-reaction. The code is validated with a series of tests, and it is expected to be primarily applicable to studying particle acceleration and transport in systems where gyroresonance is considered insignificant. We also present preliminary studies of particle acceleration during nonrelativistic magnetic reconnection.