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| Format: | Preprint |
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2024
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| Online Access: | https://arxiv.org/abs/2411.18258 |
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| _version_ | 1866912134792740864 |
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| author | Li, Jia-Wen Cao, Xinwu |
| author_facet | Li, Jia-Wen Cao, Xinwu |
| contents | The magnetically arrested disks (MADs) have attracted much attention in recent years. The formation of MADs are usually attributed to the accumulation of a sufficient amount of dynamically significant poloidal magnetic flux. In this work, the magnetic flux transport within an advection dominated accretion flow and the formation of a MAD are investigated. The structure and dynamics of an inner MAD connected with an outer ADAF are derived by solving a set of differential equations with suitable boundary conditions. We find that an inner MAD disk is eventually formed at a region about several ten Schwarzschild radius outside the horizon. Due to the presence of strong large-scale magnetic field, the radial velocity of the accretion flow is significantly decreased. The angular velocity of the MAD region is highly subkeplerian with $Ω\sim (0.4-0.5)Ω_{\rm K}$ and the corresponding ratio of gas to magnetic pressure is about $β\lesssim 1$. Also, we find that MAD is unlikely to be formed through the inward flux advection process when the external magnetic field strength weak enough with $β_{\rm out}\gtrsim 100$ around $R_{\rm out}\sim 1000R_{\rm s}$. Based on the rough estimate, we find that the jet power of a black hole, with mass $M_{\rm BH}$ and spin $a_*$, surrounded by an ADAF with inner MAD region is about two order of magnitude larger than that of a black hole surrounded by a normal ADAF. This may account for the powerful jets observed in some Fanaroff Riley type I galaxies with a very low Eddington ratio. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2411_18258 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Magnetic Flux Transport in Advection Dominated Accretion Flow Towards the Formation of Magnetically Arrested Disk Li, Jia-Wen Cao, Xinwu High Energy Astrophysical Phenomena The magnetically arrested disks (MADs) have attracted much attention in recent years. The formation of MADs are usually attributed to the accumulation of a sufficient amount of dynamically significant poloidal magnetic flux. In this work, the magnetic flux transport within an advection dominated accretion flow and the formation of a MAD are investigated. The structure and dynamics of an inner MAD connected with an outer ADAF are derived by solving a set of differential equations with suitable boundary conditions. We find that an inner MAD disk is eventually formed at a region about several ten Schwarzschild radius outside the horizon. Due to the presence of strong large-scale magnetic field, the radial velocity of the accretion flow is significantly decreased. The angular velocity of the MAD region is highly subkeplerian with $Ω\sim (0.4-0.5)Ω_{\rm K}$ and the corresponding ratio of gas to magnetic pressure is about $β\lesssim 1$. Also, we find that MAD is unlikely to be formed through the inward flux advection process when the external magnetic field strength weak enough with $β_{\rm out}\gtrsim 100$ around $R_{\rm out}\sim 1000R_{\rm s}$. Based on the rough estimate, we find that the jet power of a black hole, with mass $M_{\rm BH}$ and spin $a_*$, surrounded by an ADAF with inner MAD region is about two order of magnitude larger than that of a black hole surrounded by a normal ADAF. This may account for the powerful jets observed in some Fanaroff Riley type I galaxies with a very low Eddington ratio. |
| title | Magnetic Flux Transport in Advection Dominated Accretion Flow Towards the Formation of Magnetically Arrested Disk |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2411.18258 |