MG15 - Talk detail |
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Participant |
Pugliese, Daniela | |||||||
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Institution |
Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Faculty of Philosophy\&Science, - Bezrucovo namesti 13 - Opava - - Czech Republic | |||||||
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Session |
BH5 |
Accepted |
Yes |
Order |
6 |
Time |
17:35 | 20' |
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Talk |
Oral abstract |
Title |
Ergoregion in the Kerr spacetime: investigation on Killing horizons, Killing throat and bottlenecks in Naked singularities. | |||||
| Coauthors | Pugliese, Daniela; Quevedo Hernando | |||||||
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Abstract |
Black holes (BHs) and Naked singularity (NSs) properties are investigated considering stationary observers in axis-symmetric Kerr spacetimes and their limiting orbital frequencies, associated with photon orbits (light surfaces). We reconsider the BH Killing horizons definition from a special perspective introducing the NS Killing's throat and Killing bottleneck for slow spinning, ``weak'', naked singularities, in analogy with the Killing's horizon definitions for axis-symmetric black holes. This scenario is detailed on the equatorial plane of the Kerr geometries. In order to evaluate the effects of frame- dragging as the cause of Killing bottleneck and the horizons properties the investigation is focused on the ergoregion of the Kerr geometries. These results, we believe, can have significance in comprehension of the formation and eventually destruction processes of the BHs Killing horizons. |
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Pdf file |
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Session |
AC3 |
Accepted |
Yes |
Order |
5 |
Time |
17:15 | 20' |
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Talk |
Oral abstract |
Title |
Multi-accretion events from corotating and counterrotating SMBHs tori | |||||
| Coauthors | Pugliese, Daniela; Zdenek Stuchlík | |||||||
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Abstract |
Ringed accretion disks (RADs), are aggregates of corotating and counterrotating toroidal accretion disks orbiting around a central Kerr super-massive Black Hole (SMBH) in AGNs. The dimensionless spin of the central BH and the fluids relative rotation proved to strongly affect the RAD dynamics. More generally there is evidence of a strict correlation between SMBH spin, fluid rotation and magnetic fields in RADs formation and evolution. Recently, the model was extended to consider RADs constituted by several magnetized accretion tori and the effects of a toroidal magnetic field in RAD dynamics have been investigated. The analysis poses constraints on tori formation and emergence of RADs instabilities in the phases of accretion onto the central attractor and tori collision emergence. Magnetic fields and fluids rotation are proved to be strongly constrained and influence tori formation and evolution in RADs, depending on the toroidal magnetic fields parameters. Eventually the RAD frame investigation constraints specific classes of tori that could be observed around some specific SMBHs identified by their dimensionless spin. Main references: D. Pugliese, Z. Stuchlík. Astrophys.J.Suppl. 229 (2017) no.2, 40; D. Pugliese, Z. Stuchlík Astrophys.J.Suppl. 221 (2015) 25; D Pugliese G Montani MNRAS, 476, 4, (2018), 4346–4361. |
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Pdf file |
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