A Numerical Model for the Dynamics of Pickup Ions Outside the Heliopause and IBEX “Ribbon” Observation
The leading mechanism for the origin of the Interstellar Boundary Explorer (IBEX) “ribbon” of enhanced energetic neutral atoms (ENAs) from the outer heliosphere is the so-called secondary ENA process. In this mechanism, neutralized ions escape the heliosphere, and after several times of charge excha...
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2025-01-01
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| author | Yifan Huang Fan Guo Eric J. Zirnstein Sung Jun Noh Hui Li Daniel B. Reisenfeld Jacob Heerikhuisen |
| author_facet | Yifan Huang Fan Guo Eric J. Zirnstein Sung Jun Noh Hui Li Daniel B. Reisenfeld Jacob Heerikhuisen |
| author_sort | Yifan Huang |
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| description | The leading mechanism for the origin of the Interstellar Boundary Explorer (IBEX) “ribbon” of enhanced energetic neutral atoms (ENAs) from the outer heliosphere is the so-called secondary ENA process. In this mechanism, neutralized ions escape the heliosphere, and after several times of charge exchange collision,s some propagate back toward Earth in directions nearly perpendicular to the local interstellar magnetic field. However, the physical processes governing the distribution of the pickup ions (PUIs) outside the heliopause are still unclear. In this study, we build a new global model of the IBEX ribbon, where a key component is to calculate the dynamics of the PUIs outside the heliopause by solving the gyrophase-averaged focused transport equations on top of the background magnetohydrodynamic-kinetic model for the heliosphere-interstellar medium interaction. We discuss how the properties of the simulated ribbon change with different scattering parameters and show simulation results of the ENA sky maps, ribbon centers, ribbon profiles at several azimuthal slices, the ribbon ENA source region, and the velocity distribution of PUIs in the ENA source region for different scattering frequencies. Our results show that the model can provide reasonable ribbon sky maps comparable to the observed ribbon when the PUI mean free path is on the order of several thousand astronomical units. |
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| publishDate | 2025-01-01 |
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| spelling | doaj-art-f836e42bfffb4556a2d09a3049c85d112025-07-08T08:59:06ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01987219210.3847/1538-4357/addbe3A Numerical Model for the Dynamics of Pickup Ions Outside the Heliopause and IBEX “Ribbon” ObservationYifan Huang0https://orcid.org/0000-0002-0422-2925Fan Guo1https://orcid.org/0000-0003-4315-3755Eric J. Zirnstein2https://orcid.org/0000-0001-7240-0618Sung Jun Noh3https://orcid.org/0000-0002-8032-7833Hui Li4https://orcid.org/0000-0003-3556-6568Daniel B. Reisenfeld5https://orcid.org/0000-0003-1874-9450Jacob Heerikhuisen6https://orcid.org/0000-0001-7867-3633Los Alamos National Laboratory , Los Alamos, NM 87545, USA ; huangyifan06005@gmail.comLos Alamos National Laboratory , Los Alamos, NM 87545, USA ; huangyifan06005@gmail.comPrinceton University , Princeton, NJ 08544, USALos Alamos National Laboratory , Los Alamos, NM 87545, USA ; huangyifan06005@gmail.comLos Alamos National Laboratory , Los Alamos, NM 87545, USA ; huangyifan06005@gmail.comLos Alamos National Laboratory , Los Alamos, NM 87545, USA ; huangyifan06005@gmail.comUniversity of Waikato , Hillcrest, Hamilton 3216, New ZealandThe leading mechanism for the origin of the Interstellar Boundary Explorer (IBEX) “ribbon” of enhanced energetic neutral atoms (ENAs) from the outer heliosphere is the so-called secondary ENA process. In this mechanism, neutralized ions escape the heliosphere, and after several times of charge exchange collision,s some propagate back toward Earth in directions nearly perpendicular to the local interstellar magnetic field. However, the physical processes governing the distribution of the pickup ions (PUIs) outside the heliopause are still unclear. In this study, we build a new global model of the IBEX ribbon, where a key component is to calculate the dynamics of the PUIs outside the heliopause by solving the gyrophase-averaged focused transport equations on top of the background magnetohydrodynamic-kinetic model for the heliosphere-interstellar medium interaction. We discuss how the properties of the simulated ribbon change with different scattering parameters and show simulation results of the ENA sky maps, ribbon centers, ribbon profiles at several azimuthal slices, the ribbon ENA source region, and the velocity distribution of PUIs in the ENA source region for different scattering frequencies. Our results show that the model can provide reasonable ribbon sky maps comparable to the observed ribbon when the PUI mean free path is on the order of several thousand astronomical units.https://doi.org/10.3847/1538-4357/addbe3Pickup ionsHeliosphereSolar windCharge exchange ionizationInterstellar mediumSolar energetic particles |
| spellingShingle | Yifan Huang Fan Guo Eric J. Zirnstein Sung Jun Noh Hui Li Daniel B. Reisenfeld Jacob Heerikhuisen A Numerical Model for the Dynamics of Pickup Ions Outside the Heliopause and IBEX “Ribbon” Observation The Astrophysical Journal Pickup ions Heliosphere Solar wind Charge exchange ionization Interstellar medium Solar energetic particles |
| title | A Numerical Model for the Dynamics of Pickup Ions Outside the Heliopause and IBEX “Ribbon” Observation |
| title_full | A Numerical Model for the Dynamics of Pickup Ions Outside the Heliopause and IBEX “Ribbon” Observation |
| title_fullStr | A Numerical Model for the Dynamics of Pickup Ions Outside the Heliopause and IBEX “Ribbon” Observation |
| title_full_unstemmed | A Numerical Model for the Dynamics of Pickup Ions Outside the Heliopause and IBEX “Ribbon” Observation |
| title_short | A Numerical Model for the Dynamics of Pickup Ions Outside the Heliopause and IBEX “Ribbon” Observation |
| title_sort | numerical model for the dynamics of pickup ions outside the heliopause and ibex ribbon observation |
| topic | Pickup ions Heliosphere Solar wind Charge exchange ionization Interstellar medium Solar energetic particles |
| url | https://doi.org/10.3847/1538-4357/addbe3 |
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