Two-dimensional Particle-in-cell Simulations of Axisymmetric Black Hole Magnetospheres: Angular Dependence of the Blandford–Znajek Flux
We examine the temporary evolution of axisymmetric magnetospheres around rapidly rotating black holes (BHs), by applying our two-dimensional particle-in-cell simulation code. Assuming a stellar-mass BH, we find that the created pairs fail to screen the electric field along the magnetic field, provid...
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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 |
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| Online Access: | https://doi.org/10.3847/1538-4357/aca8b0 |
| _version_ | 1797701282290466816 |
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| author | Kouichi Hirotani Hsien Shang Ruben Krasnopolsky Kenichi Nishikawa |
| author_facet | Kouichi Hirotani Hsien Shang Ruben Krasnopolsky Kenichi Nishikawa |
| author_sort | Kouichi Hirotani |
| collection | DOAJ |
| description | We examine the temporary evolution of axisymmetric magnetospheres around rapidly rotating black holes (BHs), by applying our two-dimensional particle-in-cell simulation code. Assuming a stellar-mass BH, we find that the created pairs fail to screen the electric field along the magnetic field, provided that the mass accretion rate is much small compared to the Eddington limit. Magnetic islands are created by reconnection near the equator and migrate toward the event horizon, expelling magnetic flux tubes from the BH vicinity during a large fraction of time. When the magnetic islands stick to the horizon due to redshift and virtually vanish, a strong magnetic field penetrates the horizon, enabling efficient extraction of energy from the BH. During this flaring phase, a BH gap appears around the inner light surface with a strong meridional return current toward the equator within the ergosphere. If the mass accretion rate is 0.025% of the Eddington limit, the BH’s spin-down luminosity becomes 16–19 times greater than its analytical estimate during the flares, although its long-term average is only 6% of it. We demonstrate that the extracted energy flux concentrates along the magnetic field lines threading the horizon in the middle latitudes. It is implied that this meridional concentration of the Poynting flux may result in the formation of limb-brightened jets from low-accreting BH systems. |
| first_indexed | 2024-03-12T04:34:11Z |
| format | Article |
| id | doaj.art-c97ae73ad9f445d1b3bd8a2c9b702848 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T04:34:11Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-c97ae73ad9f445d1b3bd8a2c9b7028482023-09-03T09:58:13ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-01943216410.3847/1538-4357/aca8b0Two-dimensional Particle-in-cell Simulations of Axisymmetric Black Hole Magnetospheres: Angular Dependence of the Blandford–Znajek FluxKouichi Hirotani0https://orcid.org/0000-0002-2472-9002Hsien Shang1https://orcid.org/0000-0001-8385-9838Ruben Krasnopolsky2https://orcid.org/0000-0001-5557-5387Kenichi Nishikawa3https://orcid.org/0000-0001-6031-7040Institute of Astronomy and Astrophysics , Academia Sinica, Taipei 10617, Taiwan, Republic of China ; hirotani,shang@asiaa.sinica.eduInstitute of Astronomy and Astrophysics , Academia Sinica, Taipei 10617, Taiwan, Republic of China ; hirotani,shang@asiaa.sinica.eduInstitute of Astronomy and Astrophysics , Academia Sinica, Taipei 10617, Taiwan, Republic of China ; hirotani,shang@asiaa.sinica.eduDepartment of Physics, Chemistry and Mathematics, Alabama A&M University , Huntsville, AL 35811, USAWe examine the temporary evolution of axisymmetric magnetospheres around rapidly rotating black holes (BHs), by applying our two-dimensional particle-in-cell simulation code. Assuming a stellar-mass BH, we find that the created pairs fail to screen the electric field along the magnetic field, provided that the mass accretion rate is much small compared to the Eddington limit. Magnetic islands are created by reconnection near the equator and migrate toward the event horizon, expelling magnetic flux tubes from the BH vicinity during a large fraction of time. When the magnetic islands stick to the horizon due to redshift and virtually vanish, a strong magnetic field penetrates the horizon, enabling efficient extraction of energy from the BH. During this flaring phase, a BH gap appears around the inner light surface with a strong meridional return current toward the equator within the ergosphere. If the mass accretion rate is 0.025% of the Eddington limit, the BH’s spin-down luminosity becomes 16–19 times greater than its analytical estimate during the flares, although its long-term average is only 6% of it. We demonstrate that the extracted energy flux concentrates along the magnetic field lines threading the horizon in the middle latitudes. It is implied that this meridional concentration of the Poynting flux may result in the formation of limb-brightened jets from low-accreting BH systems.https://doi.org/10.3847/1538-4357/aca8b0Kerr black holesMagnetic fieldsGeneral relativityRelativistic jetsPlasma astrophysicsHigh energy astrophysics |
| spellingShingle | Kouichi Hirotani Hsien Shang Ruben Krasnopolsky Kenichi Nishikawa Two-dimensional Particle-in-cell Simulations of Axisymmetric Black Hole Magnetospheres: Angular Dependence of the Blandford–Znajek Flux The Astrophysical Journal Kerr black holes Magnetic fields General relativity Relativistic jets Plasma astrophysics High energy astrophysics |
| title | Two-dimensional Particle-in-cell Simulations of Axisymmetric Black Hole Magnetospheres: Angular Dependence of the Blandford–Znajek Flux |
| title_full | Two-dimensional Particle-in-cell Simulations of Axisymmetric Black Hole Magnetospheres: Angular Dependence of the Blandford–Znajek Flux |
| title_fullStr | Two-dimensional Particle-in-cell Simulations of Axisymmetric Black Hole Magnetospheres: Angular Dependence of the Blandford–Znajek Flux |
| title_full_unstemmed | Two-dimensional Particle-in-cell Simulations of Axisymmetric Black Hole Magnetospheres: Angular Dependence of the Blandford–Znajek Flux |
| title_short | Two-dimensional Particle-in-cell Simulations of Axisymmetric Black Hole Magnetospheres: Angular Dependence of the Blandford–Znajek Flux |
| title_sort | two dimensional particle in cell simulations of axisymmetric black hole magnetospheres angular dependence of the blandford znajek flux |
| topic | Kerr black holes Magnetic fields General relativity Relativistic jets Plasma astrophysics High energy astrophysics |
| url | https://doi.org/10.3847/1538-4357/aca8b0 |
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