Study of Asymptotic Velocity in the Bondi–Hoyle Accretion Flows in the Domain of Kerr and 4-D Einstein–Gauss–Bonnet Gravities

Dönmez, Orhan; Doğan, Fatih; Sahin, Tuba

doi:10.3390/universe8090458

Cited by 9 publications

(14 citation statements)

References 120 publications

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“…The Horndeski black hole reveals the effects of both the rotation of the black hole and the hair parameters on the formed shock cone. Thus, our aim is to provide explanations for the physical mechanisms of the observed QPO frequencies, which differ from our previous studies [19,27,28,47,48]. When modeling the shock cone around the Horndeski black hole, the matter is sent from the upstream region with spherical accretion from the outer boundary of the computational domain.…”

Section: Initial and Boundary Conditionsmentioning

confidence: 89%

“…Subsequently, it has exhibited instability behavior around the certain value. Drawing from extensive experience with QPOs, we are confident that QPO frequencies do not depend on grid resolution [26][27][28]51].…”

Section: Initial and Boundary Conditionsmentioning

confidence: 92%

“…During the formation of the shock cone in BHL accretion, V ∞ /c plays a significant role in creating an effect. This effect has been extensively discussed in the literature across the different gravities [16,18,19,[22][23][24][25][26][49][50][51]. However, in our upcoming article, we will extensively discuss the impact of V ∞ /c, considering the scalar hair and the rotation parameter of the black hole as well.…”

Section: Initial and Boundary Conditionsmentioning

confidence: 94%

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Bondi–Hoyle accretion around the non-rotating black hole in 4D Einstein–Gauss–Bonnet gravity

Dönmez

2021

Eur. Phys. J. C

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In this paper, the numerical investigation of a Bondi–Hoyle accretion around a non-rotating black hole in a novel four dimensional Einstein–Gauss–Bonnet gravity is investigated by solving the general relativistic hydrodynamical equations using the high resolution shock capturing scheme. For this purpose, the accreated matter from the wind-accreating X-ray binaries falls towards the black hole from the far upstream side of the domain, supersonically. We study the effects of Gauss–Bonnet coupling constant $$\alpha $$ α in 4D EGB gravity on the accreated matter and shock cones created in the downstream region in detail. The required time having the shock cone in downstream region is getting smaller for $$\alpha > 0$$ α > 0 while it is increasing for $$\alpha < 0$$ α < 0 . It is found that increases in $$\alpha $$ α leads violent oscillations inside the shock cone and increases the accretion efficiency. The violent oscillations would cause increase in the energy flux, temperature, and spectrum of X-rays. So the quasi-periodic oscillations (QPOs) are naturally produced inside the shock cone when $$-5 \le \alpha \le 0.8$$ - 5 ≤ α ≤ 0.8 . It is also confirmed that EGB black hole solution converges to the Schwarzschild one in general relativity when $$\alpha \rightarrow 0$$ α → 0 . Besides, the negative coupling constants also give reasonable physical solutions and increase of $$\alpha $$ α in negative directions suppresses the possible oscillation observed in the shock cone.

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Section: Initial and Boundary Conditionsmentioning

confidence: 89%

Section: Initial and Boundary Conditionsmentioning

confidence: 92%

Section: Initial and Boundary Conditionsmentioning

confidence: 94%

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Bondi–Hoyle accretion around the non-rotating black hole in 4D Einstein–Gauss–Bonnet gravity

Dönmez

2021

Eur. Phys. J. C

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“…See e.g. [850] for a recent review of the theory, [851][852][853][854][855][856][857][858][859][860] for important discussions on possible pathologies associated to the rescaling procedure, and [861][862][863][864][865][866][867][868][869][870][871][872][873][874][875][876][877][878][879][880] for other important works on the theory. With all the caveats discussed in [851,853,[855][856][857][858][859] in mind, static spherically symmetric solutions within 4DEGB gravity have been studied, and the metric function is given by the following (see e.g.…”

Section: D Einstein-gauss-bonnet Gravitymentioning

confidence: 99%

Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A ∗

Vagnozzi

Roy

Tsai

et al. 2023

Class. Quantum Grav.

227

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Horizon-scale images of black holes (BHs) and their shadows have opened an unprecedented window onto tests of gravity and fundamental physics in the strong-field regime. We consider a wide range of well-motivated deviations from classical General Relativity (GR) BH solutions, and constrain them using the Event Horizon Telescope (EHT) observations of Sagittarius A* (Sgr A*), connecting the size of the bright ring of emission to that of the underlying BH shadow and exploiting high-precision measurements of Sgr A*’s mass-to-distance ratio. The scenarios we consider, and whose fundamental parameters we constrain, include various regular BHs, string-inspired space-times, violations of the no-hair theorem driven by additional fields, alternative theories of gravity, novel fundamental physics frameworks, and BH mimickers including well-motivated wormhole and naked singularity space-times. We demonstrate that the EHT image of Sgr A* places particularly stringent constraints on models predicting a shadow size larger than that of a Schwarzschild BH of a given mass, with the resulting limits in some cases surpassing cosmological ones. Our results are among the first tests of fundamental physics from the shadow of Sgr A* and, while the latter appears to be in excellent agreement with the predictions of GR, we have shown that a number of well-motivated alternative scenarios, including BH mimickers, are far from being ruled out at present.

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“…The numerical solution of general relativistic hydrodynamic equations plays a crucial role in understanding the origin of QPOs in the vicinity of black holes [8][9][10][11][12][13]. By solving these equations, researchers can explore the dynamic structure of the accretion disk around black holes, the presence of shock waves, and other chaotic conditions that arise in regions close to the black hole event horizon, where gravity is extremely strong [14][15][16][17][18][19][20][21][22][23][24][25]. Lowand high-frequency QPOs, significant phenomena observed in these systems, have been a subject of extensive research in the literature [4,[26][27][28].…”

Section: Introductionmentioning

confidence: 99%

The Shock Cone Instabilities and Quasi-Periodic Oscillations around the Hartle–Thorne Black Hole

Donmez,

Dogan

2024

Universe

Self Cite

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To explain the observed X-ray data in a black hole–accreting matter system and understand the physical mechanisms behind QPOs, we have numerically modeled the dynamical and oscillation properties of the shock cone formed around both slowly and rapidly rotating Hartle–Thorne black holes, resulting from the mechanism of Bondi–Hoyle–Lyttleton (BHL). According to the numerical simulations, an increase in the quadrupole parameter leads to a decrease in the shock cone opening angle around the black hole. A larger quadrupole parameter results in more matter falling into the black hole within the cone. The combination of the quadrupole parameter and black hole rotation causes the matter inside the cone to exhibit chaotic motion. These dynamical changes and chaotic behavior of the shock cones excite the fundamental oscillation modes. Moreover, new frequencies have been formed due to the nonlinear coupling of the fundamental modes. Conversely, we have numerically studied the behavior of cones formed around rapidly rotating Hartle–Thorne black holes and found differences and similarities to those obtained from slowly rotating cases. Finally, comparing the outcomes obtained fromHartle–Thorne gravity with the results fromKerr and Einstein–Gauss–Bonnet (EGB) gravities reveals the impact of the quadrupole parameter on the shock cone and QPOs.

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Study of Asymptotic Velocity in the Bondi–Hoyle Accretion Flows in the Domain of Kerr and 4-D Einstein–Gauss–Bonnet Gravities

Cited by 9 publications

References 120 publications

Bondi–Hoyle accretion around the non-rotating black hole in 4D Einstein–Gauss–Bonnet gravity

Bondi–Hoyle accretion around the non-rotating black hole in 4D Einstein–Gauss–Bonnet gravity

Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A ∗

The Shock Cone Instabilities and Quasi-Periodic Oscillations around the Hartle–Thorne Black Hole

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