12-20 July 2017
BEXCO
Asia/Seoul timezone
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Contribution

BEXCO - Room C(109/110)

[SH011] A numerical investigation of cosmic ray modulation near the heliopause

Speakers

  • Xi LUO

Primary authors

  • Xi LUO (North-West University, South Africa, National Space Science Center, Chinese Academy of Science, China)

Co-authors

Description

A hybrid transport model is used for studying the modulation of galactic cosmic ray in the global heliosphere. This model incorporates the simulation data from a comprehensive MagnetoHydroDynamics (MHD) model with the traditional cosmic ray transport model, which solve the Parker’s transport equation using a Stochastic Differential Equations (SDE) approach. Since the MHD simulation data includes the outer heliosheath region, this hybrid model can be used to study the transport of galactic cosmic rays near the heliopause (HP). We find that the simulated radial flux near the HP increases when increasing the ratio of the parallel to the perpendicular diffusion coefficients in the outer heliosheath. As the multiplying factor of this ratio reaches 10e10, the cosmic ray radial flux experiences a sudden upwards jump near the HP, similar to what Voyager 1 had observed in 2012. We simulate the cosmic ray radial flux along different directions in the heliosphere. There is not a well-defined thin layer between the solar wind region and interstellar region along the tail and polar directions of the heliosphere. We also simulate the cosmic ray radial flux for different energy values along the direction of Voyager 1. We find that there is little modulation happened beyond the HP. After increasing the ratio of the mentioned diffusion coefficients beyond the HP, more pseudo-particles in our SDE approach, which have been traced from the upwind nose region, exit in the downwind tail region. It can be inferred that the cosmic ray particles observed by Voyager 1 at the nose region diffuse directly from the tail region.