Remote sensing: a new feature caused by the GMIR on cosmic ray transport in the heliosheath Xi Luo1, Ming Zhang1, Hamid K. Rassoul1, and N.V. Pogorelov2 1Florida Institute of Technology 2University of Alabama in Huntsville

Global Merged Interaction Region GMIR are the diffusion barriers of cosmic ray. It has high solar wind speed and density. It is believed that GMIR is partly formed by the large coronal mass ejection( Lara et. al., APJ. 2005). 关于Global Merged Interaction Region 的定义也许可以找到一些updated的information

Modern cosmic ray transport theory treats GMIR as a diffusion barrier to explain the CR intensity decrease inside GMIR. Adapting this concept, the step decrease of the cosmic ray intensity during the ascending phase of the solar maximum can be well simulated. However, previous understandings about GMIR are mainly confined inside the termination shock. As Voyagers crossed the Termination Shock, entering into the vast region called heliosheath, it is worthwhile to move our attention there, and study the cosmic ray transport, such as GMIR effects inside heliosheath.

Parker’s Transport Theory Energetic particles random walk in the Interplanetary Magnetic Field. Fokker-Planck equation Distribution function, Phase space Solar wind speed, cosmic ray drift Speed Momentum Diffusion Tensor Convected term, adiabatic cooling term, diffusion term and drift term are included

Equivalent to Parker’s Equation Stochastic Differential Equation for pseudo individual cosmic ray particles Equivalent to Parker’s Equation In order to know the physical value at one location, thousands of particles needed to be traced.

Background Plasma A Solar Wind B Magnetic Field & Current Sheet

Simulation Model-GMIR Figure 1: GMIR model used in our simulation. 1A) is a snapshot of plasma speed along Voyager 1 direction, as GMIR is located at 60 AU. 1B) shows how the shock strength varies with the radius. The GMIR shock has a peak-like shape. 1C) shows the profile of how shock strength change with latitude. 1D) shows the time profile of plasma speed at 99AU as a GMIR pass by.

Simulation Model-GMIR (Magnetic Field profile) The Magnetic field profile. The upper panel roughly along Voyager 1 direction. The lower panel shows the magnetic field change as a GMIR passes by.

Simulation Model-GMIR B Dynamic Profile GMIR can propagate inside the heliosphere. We adopt a model proposed by Whang and Lu (1999). The GMIR shock speed and strength both decrease as it propagates. At termination shock, we assume the shock speed and strength experience a sudden decrease. After that, the GMIR shock propagates constantly in the heliosheath.

Ⅰ In the supersonic solar wind region (Put an artificial spacecraft at 60AU) Following figure shows that as GMIR passes by, the cosmic ray flux decreases, and the starting point coincides with the GMIR front arrival (plasma speed begin to increase). This scenario agrees with our previous understanding of GMIR effect.

Ⅱ In the heliosheath region (put an artificial spacecraft at 99AU) Although the main scenario is similar to the case inside the termination shock, the starting time of cosmic ray flux decrease is ahead of GMIR’s arrival, roughly at t=0, when the GMIR arrives at termination shock. The time profile of cosmic ray flux at 99 AU as GMIR passes by. t =0

Voyagers’ Observation The 2006 GMIR event , cosmic ray intensity, solar wind speed, solar wind density, magnetic field for the Voyager 2 spacecraft. The Voyagers’ Galactic Cosmic Ray intensity in 2006. The vertical line labels the transient decrease caused by GMIR, and V1’s 2006.29 transient decrease is caused by GMIR’s arrival at Termination Shock.

Demonstration of 2006’s Voyagers location comparison with TS and GMIR

Voyager 2’s measurements in 2006 Rankine–Hugoniot relationship Determining the location of TS(The mistake of 2006.29 – 2006.19) Voyager 2’s measurements in 2006

Demonstration of the radial distance of the termination shock along V1 direction 91 AU

Conclusion A GMIR model was incorporated into the modulation model to study to GMIR effect on cosmic ray transport in the heliosheath. This enables us to find as GMIR arrives at TS, it will have remote effect on cosmic ray transport in the heliosheath. Using this feature, the location of TS along voyager 1 in 2006 was estimated, roughly 91AU, comparing 94AU in the end of 2004, TS moved inward 3AU. In addition, the propagation speed of GMIR inside TS (572km/s) and outside TS(172km/s) can also be estimated .

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