Study cosmic ray modulation near the heliopause: A numerical approach

By incorporating the MagnetoHydroDynamic (MHD) global heliospheric data into the Parker's cosmic-rays (CRs) transport equation, we constructed a hybrid galactic cosmic ray transport model to study the galactic cosmic-rays (GCR) behaviour near the heliopause(HP). Based on this hybrid model, we found that: (1)By increasing the ratio of the parallel diffusion coefficient to the perpendicular diffusion coefficient in the outer heliosheath (the region near HP and beyond), the simulated radial flux gradient near the HP increases as well. As this ratio multiplying factor reaches 10¹⁰, the flux experiences a sudden jump near the HP, similar to what Voyager 1 had observed in 2012. (2)After increasing the ratio of the diffusion coefficients beyond the HP, more pseudo-particles in our numerical approach which have been traced from the upwind nose region exit in the downwind tail region. It is thus possible that they diffuse more directly from the tail region to the nose region.