Study of Asymptotic Velocity in the Bondi–Hoyle Accretion Flows in the Domain of Kerr and 4-D Einstein–Gauss–Bonnet Gravities
Understanding the physical structures of the accreted matter very close to a black hole in quasars and active galactic nucleus (AGN) is an important milestone to constrain the activities occurring in their centers. In this paper, we numerically investigate the effects of the asymptotic velocities on...
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MDPI AG
2022-09-01
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| Series: | Universe |
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| Online Access: | https://www.mdpi.com/2218-1997/8/9/458 |
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| author | Orhan Donmez Fatih Dogan Tuba Sahin |
| author_facet | Orhan Donmez Fatih Dogan Tuba Sahin |
| author_sort | Orhan Donmez |
| collection | DOAJ |
| description | Understanding the physical structures of the accreted matter very close to a black hole in quasars and active galactic nucleus (AGN) is an important milestone to constrain the activities occurring in their centers. In this paper, we numerically investigate the effects of the asymptotic velocities on the physical structures of the accretion disk around the Kerr and Einstein–Gauss–Bonnet (EGB) rapidly rotating black holes. The Bondi–Hoyle accretion is considered with a falling gas towards the black hole in an upstream region of the computational domain. Shock cones are naturally formed in the downstream part of the flow around both black holes. The structure of the cones and the amount of the accreted matter depend on asymptotic velocity <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>V</mi><mo>∞</mo></msub></semantics></math></inline-formula> (Mach number) and the types of the gravities (Kerr or EGB). Increasing the Mach number of the in-flowing matter in the supersonic region reduces the shock opening angle and the accretion rates, because of the gas rapidly falling towards the black hole. The EGB gravity leads to an increase in the shock opening angle of the shock cones while the mass-accretion rates <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>d</mi><mi>M</mi><mo>/</mo><mi>d</mi><mi>t</mi></mrow></semantics></math></inline-formula> decrease in EGB gravity with a Gauss–Bonnet (GB) coupling constant <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>α</mi></semantics></math></inline-formula>. It is also confirmed that accretion rates and drag forces are significantly altered in the EGB gravity. Our numerical simulation results could be used in identifying the accretion mechanism and physical properties of the accretion disk and black hole in the observed X-rays such as NGC 1313 X-1 and 1313 X-2 and MAXI J1803-298. |
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| issn | 2218-1997 |
| language | English |
| last_indexed | 2024-03-09T22:18:40Z |
| publishDate | 2022-09-01 |
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| spelling | doaj.art-e6f7851ef9e746069d723b1cc63df7e62023-11-23T19:18:51ZengMDPI AGUniverse2218-19972022-09-018945810.3390/universe8090458Study of Asymptotic Velocity in the Bondi–Hoyle Accretion Flows in the Domain of Kerr and 4-D Einstein–Gauss–Bonnet GravitiesOrhan Donmez0Fatih Dogan1Tuba Sahin2College of Engineering and Technology, American University of the Middle East, KuwaitCollege of Engineering and Technology, American University of the Middle East, KuwaitCollege of Engineering and Technology, American University of the Middle East, KuwaitUnderstanding the physical structures of the accreted matter very close to a black hole in quasars and active galactic nucleus (AGN) is an important milestone to constrain the activities occurring in their centers. In this paper, we numerically investigate the effects of the asymptotic velocities on the physical structures of the accretion disk around the Kerr and Einstein–Gauss–Bonnet (EGB) rapidly rotating black holes. The Bondi–Hoyle accretion is considered with a falling gas towards the black hole in an upstream region of the computational domain. Shock cones are naturally formed in the downstream part of the flow around both black holes. The structure of the cones and the amount of the accreted matter depend on asymptotic velocity <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>V</mi><mo>∞</mo></msub></semantics></math></inline-formula> (Mach number) and the types of the gravities (Kerr or EGB). Increasing the Mach number of the in-flowing matter in the supersonic region reduces the shock opening angle and the accretion rates, because of the gas rapidly falling towards the black hole. The EGB gravity leads to an increase in the shock opening angle of the shock cones while the mass-accretion rates <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>d</mi><mi>M</mi><mo>/</mo><mi>d</mi><mi>t</mi></mrow></semantics></math></inline-formula> decrease in EGB gravity with a Gauss–Bonnet (GB) coupling constant <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>α</mi></semantics></math></inline-formula>. It is also confirmed that accretion rates and drag forces are significantly altered in the EGB gravity. Our numerical simulation results could be used in identifying the accretion mechanism and physical properties of the accretion disk and black hole in the observed X-rays such as NGC 1313 X-1 and 1313 X-2 and MAXI J1803-298.https://www.mdpi.com/2218-1997/8/9/458rotating black holeEGB gravityshock conenumerical relativityX-ray |
| spellingShingle | Orhan Donmez Fatih Dogan Tuba Sahin Study of Asymptotic Velocity in the Bondi–Hoyle Accretion Flows in the Domain of Kerr and 4-D Einstein–Gauss–Bonnet Gravities Universe rotating black hole EGB gravity shock cone numerical relativity X-ray |
| title | Study of Asymptotic Velocity in the Bondi–Hoyle Accretion Flows in the Domain of Kerr and 4-D Einstein–Gauss–Bonnet Gravities |
| title_full | Study of Asymptotic Velocity in the Bondi–Hoyle Accretion Flows in the Domain of Kerr and 4-D Einstein–Gauss–Bonnet Gravities |
| title_fullStr | Study of Asymptotic Velocity in the Bondi–Hoyle Accretion Flows in the Domain of Kerr and 4-D Einstein–Gauss–Bonnet Gravities |
| title_full_unstemmed | Study of Asymptotic Velocity in the Bondi–Hoyle Accretion Flows in the Domain of Kerr and 4-D Einstein–Gauss–Bonnet Gravities |
| title_short | Study of Asymptotic Velocity in the Bondi–Hoyle Accretion Flows in the Domain of Kerr and 4-D Einstein–Gauss–Bonnet Gravities |
| title_sort | study of asymptotic velocity in the bondi hoyle accretion flows in the domain of kerr and 4 d einstein gauss bonnet gravities |
| topic | rotating black hole EGB gravity shock cone numerical relativity X-ray |
| url | https://www.mdpi.com/2218-1997/8/9/458 |
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