Authors: Weihao Liu (University of Michigan), Igor V. Sokolov (University of Michigan), Ofer Cohen (University of Massachusetts Lowell), Lulu Zhao (University of Michigan), Tamas Gombosi (University of Michigan)

The solar disk is a bright source of multi-GeV and TeV gamma rays, due to the interactions of high-energy Galactic Cosmic Rays (GCRs) with the chromo- and photo-sphere plasmas of the Sun. However, the underlying production mechanisms remain incompletely understood, except that the emission efficiency must be greatly enhanced by magnetic fields that redirect some GCR particles from ingoing to outgoing before their interaction with the solar atmosphere. To elaborate the nature of the solar gamma-ray emission, we perform a numerical study using a newly developed scheme in the Space Weather Modeling Framework (SWMF) and the most recent Monte Carlo nuclear code, FLUKA. Specifically, the newly developed scheme in SWMF can make good use of the outputs of MagnetoHydroDynamics (MHD) simulations in the Solar Corona (SC) and Inner Heliosphere (IH), and simulate the GCR spectrum from IH to the region very close to the Sun. The FLUKA package serves to simulate the propagation and interactions of GCR particles with the Sun. Our finding will carry significant implications for understanding the propagation of energetic particles in the SC and IH regions, and can provide new insights about the local density of cosmic rays and their interactions with the Sun and its magnetic environment.