Constructing Higher-Dimensional Exact Black Holes in Einstein-Maxwell-Scalar Theory

Qiu, Jianhui; Gao, Changjun

doi:10.3390/universe6090148

Cited by 5 publications

(4 citation statements)

References 26 publications

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“…The above study fully illustrates the motivations for the novel Einstein Maxwell-scalar theory S 3 [35][36][37], as well as the connection between it and the dilaton model. Now, let us extend our grasp of this theory by considering rotation, starting with the associated static solution of S 3 , and concentrating on the search for a slowly rotating black hole solution in asymptotically flat spacetime.…”

Section: Action and The Equations Of Motionmentioning

confidence: 68%

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Slowly rotating black holes in the novel Einstein–Maxwell-scalar theory

Qiu

2021

Eur. Phys. J. C

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We investigate a slowly rotating black hole solution in a novel Einstein–Maxwell-scalar theory, which is prompted by the classification of general Einstein–Maxwell-scalar theory. The gyromagnetic ratio of this black hole is calculated, and it increases as the second free parameter $$\beta $$ β increases, but decreases with the increasing parameter $$\gamma \equiv \frac{2 \alpha ^{2}}{1+\alpha ^2}$$ γ ≡ 2 α 2 1 + α 2 . In the Einstein–Maxwell-dilaton (EMD) theory, the parameter $$\beta $$ β vanishes but the free parameter $$\alpha $$ α governing the strength of the coupling between the dilaton and the Maxwell field remains. The gyromagnetic ratio is always less than 2, the well-known value for a Kerr–Newman (KN) black hole as well as for a Dirac electron. Scalar hairs reduce the magnetic dipole moment in dilaton theory, resulting in a drop in the gyromagnetic ratio. However, we find that the gyromagnetic ratio of two can be realized in this Einstein–Maxwell-scalar theory by increasing $$\beta $$ β and the charge-to-mass ratio Q/M simultaneously (recall that the gyromagnetic ratio of KN black holes is independent of Q/M). The same situation also applies to the angular velocity of a locally non-rotating observer. Moreover, we analyze the period correction for circular orbits in terms of charge-to-mass ratio, as well as the correction of the radius of the innermost stable circular orbits. It is found the correction increases with $$\beta $$ β but decreases with Q/M. Finally, the total radiative efficiency is investigated, and it can vanish once the effect of rotation is considered.

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Section: Action and The Equations Of Motionmentioning

confidence: 68%

“…Turimov et al [36] have investigated the geodesic of this theory. We extended it by combining RN BHs and general dilaton BHs [35] and by considering higher dimensions [37]. The present article is devoted to the study of the slowly rotating black hole in four-dimensional and asymptotically flat spacetime.…”

Section: Introductionmentioning

confidence: 99%

Slowly rotating black holes in the novel Einstein–Maxwell-scalar theory

Qiu

2021

Eur. Phys. J. C

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“…The magnetic dipole moment for this asymptotically AdS slowly rotating black hole can be defined as [40] and J = − ǫ 6 const into above equation, we obtain g = −6 (b+(1−γ)a) const . We have shown the behavior of the gyromagnetic ratio g of the black holes versus γ in Fig.…”

Section: A Angular Momentum Gyromagnetic Ratio and Angular Velocitymentioning

confidence: 96%

“…Recently, by observing the Reissner Nordstrom solution, the Einstein-Maxwell-dilaton solution, the dilaton black holes in the anti-de Sitter universe in four dimensions [37] and arbitrary dimensions [38], we construct a new Einstein-Maxwell-Scalar theory in four dimensions [39] and arbitrary dimensions [40]. The coupling between scalar field and Maxwell field can be viewed as an extension of coupling between dilaton and Maxwell field.…”

Section: Introductionmentioning

confidence: 99%

Slowly rotating black holes in the Einstein-Maxwell-scalar theory

Qiu

2021

Preprint

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We make the research on a slowly rotating black hole solution in a new Einstein-Maxwell-scalar theory, which is an extension of the Einstein-Maxwell-dilaton theory. The gyromagnetic ratio of this black hole is calculated and it increases with the parameter β, but decreases with the parameter γ. In the Einstein-Maxwell-dilaton theory where the parameter β is in the absence, the gyromagnetic ratio is always less than 2, the gyromagnetic ratio for Kerr-Newman black hole. Now we find that the standard gyromagnetic ratio 2 can also be realized in this Einstein-Maxwell-scalar theory by increasing β and γ simultaneously. The same value of angular velocity of locally non-rotating observer as that in Kerr-Newman black hole can also be obtained in the same way. We also investigated the correction of period for circular orbits with respect to charge to mass ratio and the correction of radius of innermost stable circular orbits. We find that the correction becomes smaller and smaller with the increase of β. It is also shown that the radiative efficiency in the thin accretion disk model, for small value of β and large value of charge to mass ratio, the efficiency vanishes due to lacking of the enough stress and dynamic friction in the accretion model. A phantom Maxwell black hole is investigated in this theory as an example of exact slowly rotating black hole solution.Therefore, formula for angular velocity of the event horizon is shown. Correction of the radius of innermost stable circular orbits and of radiative efficiency are investigated subsequently. It is found that the correction up to first order of the perturbation parameter can vanish for some value of charge-to-mass ratio. The total radiative efficiency can also vanish once the effect of rotation is considered.

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