Are GRMHD Mean-Field Dynamo Models of Thick Accretion Disks SANE?
The remarkable results by the Event Horizon Telescope collaboration concerning the emission from M87* and, more recently, its polarization properties, require an increasingly accurate modeling of the plasma flows around the accreting black hole. Radiatively inefficient sources such as M87* and Sgr A...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-07-01
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| Series: | Universe |
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| Online Access: | https://www.mdpi.com/2218-1997/7/8/259 |
| _version_ | 1797521942473867264 |
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| author | Niccolò Tomei Luca Del Zanna Matteo Bugli Niccolò Bucciantini |
| author_facet | Niccolò Tomei Luca Del Zanna Matteo Bugli Niccolò Bucciantini |
| author_sort | Niccolò Tomei |
| collection | DOAJ |
| description | The remarkable results by the Event Horizon Telescope collaboration concerning the emission from M87* and, more recently, its polarization properties, require an increasingly accurate modeling of the plasma flows around the accreting black hole. Radiatively inefficient sources such as M87* and Sgr A* are typically modeled with the SANE (standard and normal evolution) paradigm, if the accretion dynamics is smooth, or with the MAD (magnetically arrested disk) paradigm, if the black hole’s magnetosphere reacts by halting the accretion sporadically, resulting in a highly dynamical process. While the recent polarization studies seem to favor MAD models, this may not be true for all sources, and SANE accretion surely still deserves attention. In this work, we investigate the possibility of reaching the typical degree of magnetization and other accretion properties expected for SANE disks by resorting to the mean-field dynamo process in axisymmetric GRMHD simulations, which are supposed to mimic the amplifying action of an unresolved magnetorotational instability-driven turbulence. We show that it is possible to reproduce the main diagnostics present in the literature by starting from very unfavorable initial configurations, such as a purely toroidal magnetic field with negligible magnetization. |
| first_indexed | 2024-03-10T08:19:44Z |
| format | Article |
| id | doaj.art-909e5a37e6be43d0bfc892aeec0fc04c |
| institution | Directory Open Access Journal |
| issn | 2218-1997 |
| language | English |
| last_indexed | 2024-03-10T08:19:44Z |
| publishDate | 2021-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Universe |
| spelling | doaj.art-909e5a37e6be43d0bfc892aeec0fc04c2023-11-22T10:05:18ZengMDPI AGUniverse2218-19972021-07-017825910.3390/universe7080259Are GRMHD Mean-Field Dynamo Models of Thick Accretion Disks SANE?Niccolò Tomei0Luca Del Zanna1Matteo Bugli2Niccolò Bucciantini3Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Via G. Sansone 1, I-50019 Sesto Fiorentino, ItalyDipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Via G. Sansone 1, I-50019 Sesto Fiorentino, ItalyDépartement d’Astrophysique, CEA—Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette, FranceDipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Via G. Sansone 1, I-50019 Sesto Fiorentino, ItalyThe remarkable results by the Event Horizon Telescope collaboration concerning the emission from M87* and, more recently, its polarization properties, require an increasingly accurate modeling of the plasma flows around the accreting black hole. Radiatively inefficient sources such as M87* and Sgr A* are typically modeled with the SANE (standard and normal evolution) paradigm, if the accretion dynamics is smooth, or with the MAD (magnetically arrested disk) paradigm, if the black hole’s magnetosphere reacts by halting the accretion sporadically, resulting in a highly dynamical process. While the recent polarization studies seem to favor MAD models, this may not be true for all sources, and SANE accretion surely still deserves attention. In this work, we investigate the possibility of reaching the typical degree of magnetization and other accretion properties expected for SANE disks by resorting to the mean-field dynamo process in axisymmetric GRMHD simulations, which are supposed to mimic the amplifying action of an unresolved magnetorotational instability-driven turbulence. We show that it is possible to reproduce the main diagnostics present in the literature by starting from very unfavorable initial configurations, such as a purely toroidal magnetic field with negligible magnetization.https://www.mdpi.com/2218-1997/7/8/259accretion disksrelativistic processesmagnetohydrodynamics (MHD)dynamo |
| spellingShingle | Niccolò Tomei Luca Del Zanna Matteo Bugli Niccolò Bucciantini Are GRMHD Mean-Field Dynamo Models of Thick Accretion Disks SANE? Universe accretion disks relativistic processes magnetohydrodynamics (MHD) dynamo |
| title | Are GRMHD Mean-Field Dynamo Models of Thick Accretion Disks SANE? |
| title_full | Are GRMHD Mean-Field Dynamo Models of Thick Accretion Disks SANE? |
| title_fullStr | Are GRMHD Mean-Field Dynamo Models of Thick Accretion Disks SANE? |
| title_full_unstemmed | Are GRMHD Mean-Field Dynamo Models of Thick Accretion Disks SANE? |
| title_short | Are GRMHD Mean-Field Dynamo Models of Thick Accretion Disks SANE? |
| title_sort | are grmhd mean field dynamo models of thick accretion disks sane |
| topic | accretion disks relativistic processes magnetohydrodynamics (MHD) dynamo |
| url | https://www.mdpi.com/2218-1997/7/8/259 |
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