Three-dimensional Dynamics of Strongly Twisted Magnetar Magnetospheres: Kinking Flux Tubes and Global Eruptions
The origins of the various outbursts of hard X-rays from magnetars (highly magnetized neutron stars) are still unknown. We identify instabilities in relativistic magnetospheres that can explain a range of X-ray flare luminosities. Crustal surface motions can twist the magnetar magnetosphere by shift...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/accada |
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| author | J. F. Mahlmann A. A. Philippov V. Mewes B. Ripperda E. R. Most L. Sironi |
| author_facet | J. F. Mahlmann A. A. Philippov V. Mewes B. Ripperda E. R. Most L. Sironi |
| author_sort | J. F. Mahlmann |
| collection | DOAJ |
| description | The origins of the various outbursts of hard X-rays from magnetars (highly magnetized neutron stars) are still unknown. We identify instabilities in relativistic magnetospheres that can explain a range of X-ray flare luminosities. Crustal surface motions can twist the magnetar magnetosphere by shifting the frozen-in footpoints of magnetic field lines in current-carrying flux bundles. Axisymmetric (2D) magnetospheres exhibit strong eruptive dynamics, i.e., catastrophic lateral instabilities triggered by a critical footpoint displacement of ψ _crit ≳ π . In contrast, our new three-dimensional (3D) twist models with finite surface extension capture important non-axisymmetric dynamics of twisted force-free flux bundles in dipolar magnetospheres. Besides the well-established global eruption resulting (as in 2D) from lateral instabilities, such 3D structures can develop helical, kink-like dynamics, and dissipate energy locally (confined eruptions). Up to 25% of the induced twist energy is dissipated and available to power X-ray flares in powerful global eruptions, with most of our models showing an energy release in the range of the most common X-ray outbursts, ≲10 ^43 erg. Such events occur when significant energy builds up while deeply buried in the dipole magnetosphere. Less energetic outbursts likely precede powerful flares, due to intermittent instabilities and confined eruptions of a continuously twisting flux tube. Upon reaching a critical state, global eruptions produce the necessary Poynting-flux-dominated outflows required by models prescribing the fast radio burst production in the magnetar wind—for example, via relativistic magnetic reconnection or shocks. |
| first_indexed | 2024-03-12T03:25:33Z |
| format | Article |
| id | doaj.art-f760b9f28cf2439c95470a92863df299 |
| institution | Directory Open Access Journal |
| issn | 2041-8205 |
| language | English |
| last_indexed | 2024-03-12T03:25:33Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj.art-f760b9f28cf2439c95470a92863df2992023-09-03T13:40:31ZengIOP PublishingThe Astrophysical Journal Letters2041-82052023-01-019472L3410.3847/2041-8213/accadaThree-dimensional Dynamics of Strongly Twisted Magnetar Magnetospheres: Kinking Flux Tubes and Global EruptionsJ. F. Mahlmann0https://orcid.org/0000-0002-5349-7116A. A. Philippov1https://orcid.org/0000-0001-7801-0362V. Mewes2https://orcid.org/0000-0001-5869-8542B. Ripperda3https://orcid.org/0000-0002-7301-3908E. R. Most4https://orcid.org/0000-0002-0491-1210L. Sironi5https://orcid.org/0000-0002-1227-2754Department of Astrophysical Sciences, Peyton Hall, Princeton University , Princeton, NJ 08544, USA ; mahlmann@princeton.eduDepartment of Physics, University of Maryland , College Park, MD 20742, USANational Center for Computational Sciences, Oak Ridge National Laboratory , Oak Ridge, TN 37831, USADepartment of Astrophysical Sciences, Peyton Hall, Princeton University , Princeton, NJ 08544, USA ; mahlmann@princeton.edu; School of Natural Sciences, Institute for Advanced Study , Princeton, NJ 08540, USA; Center for Computational Astrophysics, Flatiron Institute , New York, NY 10010, USASchool of Natural Sciences, Institute for Advanced Study , Princeton, NJ 08540, USA; Princeton Center for Theoretical Science, Jadwin Hall, Princeton University , Princeton, NJ 08544, USA; Princeton Gravity Initiative, Jadwin Hall, Princeton University , Princeton, NJ 08544, USADepartment of Astronomy and Columbia Astrophysics Laboratory, Columbia University , New York, NY 10027, USAThe origins of the various outbursts of hard X-rays from magnetars (highly magnetized neutron stars) are still unknown. We identify instabilities in relativistic magnetospheres that can explain a range of X-ray flare luminosities. Crustal surface motions can twist the magnetar magnetosphere by shifting the frozen-in footpoints of magnetic field lines in current-carrying flux bundles. Axisymmetric (2D) magnetospheres exhibit strong eruptive dynamics, i.e., catastrophic lateral instabilities triggered by a critical footpoint displacement of ψ _crit ≳ π . In contrast, our new three-dimensional (3D) twist models with finite surface extension capture important non-axisymmetric dynamics of twisted force-free flux bundles in dipolar magnetospheres. Besides the well-established global eruption resulting (as in 2D) from lateral instabilities, such 3D structures can develop helical, kink-like dynamics, and dissipate energy locally (confined eruptions). Up to 25% of the induced twist energy is dissipated and available to power X-ray flares in powerful global eruptions, with most of our models showing an energy release in the range of the most common X-ray outbursts, ≲10 ^43 erg. Such events occur when significant energy builds up while deeply buried in the dipole magnetosphere. Less energetic outbursts likely precede powerful flares, due to intermittent instabilities and confined eruptions of a continuously twisting flux tube. Upon reaching a critical state, global eruptions produce the necessary Poynting-flux-dominated outflows required by models prescribing the fast radio burst production in the magnetar wind—for example, via relativistic magnetic reconnection or shocks.https://doi.org/10.3847/2041-8213/accadaMagnetarsPlasma astrophysicsStellar magnetic fieldsX-ray burstsMagnetohydrodynamical simulationsRadio transient sources |
| spellingShingle | J. F. Mahlmann A. A. Philippov V. Mewes B. Ripperda E. R. Most L. Sironi Three-dimensional Dynamics of Strongly Twisted Magnetar Magnetospheres: Kinking Flux Tubes and Global Eruptions The Astrophysical Journal Letters Magnetars Plasma astrophysics Stellar magnetic fields X-ray bursts Magnetohydrodynamical simulations Radio transient sources |
| title | Three-dimensional Dynamics of Strongly Twisted Magnetar Magnetospheres: Kinking Flux Tubes and Global Eruptions |
| title_full | Three-dimensional Dynamics of Strongly Twisted Magnetar Magnetospheres: Kinking Flux Tubes and Global Eruptions |
| title_fullStr | Three-dimensional Dynamics of Strongly Twisted Magnetar Magnetospheres: Kinking Flux Tubes and Global Eruptions |
| title_full_unstemmed | Three-dimensional Dynamics of Strongly Twisted Magnetar Magnetospheres: Kinking Flux Tubes and Global Eruptions |
| title_short | Three-dimensional Dynamics of Strongly Twisted Magnetar Magnetospheres: Kinking Flux Tubes and Global Eruptions |
| title_sort | three dimensional dynamics of strongly twisted magnetar magnetospheres kinking flux tubes and global eruptions |
| topic | Magnetars Plasma astrophysics Stellar magnetic fields X-ray bursts Magnetohydrodynamical simulations Radio transient sources |
| url | https://doi.org/10.3847/2041-8213/accada |
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