Rotating normal and phantom Einstein–Maxwell–dilaton black holes: Geodesic analysis

Azreg‐Aïnou, Mustapha; Haroon, Sumarna; Jamil, Mubasher; Rizwan, Muhammad

doi:10.1142/s0218271819500639

Cited by 15 publications

(16 citation statements)

References 58 publications

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“…Recently, one of us has proposed a new procedure [77,78], in which one simply drops the complexification step of the Newman-Janis algorithm. The procedure has been applied to various cases [27,40,[77][78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96]. One of the main purposes of this paper is to construct the rotating LQBH solution by using this new procedure, and then to investigate its main geometric properties and the effects of LQG on the shadow of the rotating LQBH solution.…”

Section: Introductionmentioning

confidence: 99%

Shadow and quasinormal modes of a rotating loop quantum black hole

et al. 2020

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In this paper, we construct an effective rotating loop quantum black hole (LQBH) solution, starting from the spherical symmetric LQBH by applying the Newman-Janis algorithm modified by Azreg-Aïnou's non-complexification procedure, and study the effects of loop quantum gravity (LQG) on its shadow. Given the rotating LQBH, we discuss its horizon, ergosurface, and regularity as r → 0. Depending on the values of the specific angular momentum a and the polymeric function P arising from LQG, we find that the rotating solution we obtained can represent a regular black hole, a regular extreme black hole, or a regular spacetime without horizon (a non-black-hole solution). We also study the effects of LQG and rotation, and show that, in addition to the specific angular momentum, the polymeric function also causes deformations in the size and shape of the black hole shadow. Interestingly, for a given value of a and inclination angle θ0, the apparent size of the shadow monotonically decreases, and the shadow gets more distorted with increasing P . We also consider the effects of P on the deviations from the circularity of the shadow, and find that the deviation from circularity increases with increasing P for fixed values of a and θ0. Additionally, we explore the observational implications of P in comparing with the latest Event Horizon Telescope (EHT) observation of the supermassive black hole, M87*. The connection between the shadow radius and quasinormal modes in the eikonal limit as well as the deflection of massive particles are also considered.

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Section: Introductionmentioning

confidence: 99%

Shadow and quasinormal modes of a rotating loop quantum black hole

et al. 2020

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“…In this section we generalize the static and the spherical symmetric black hole solution to a spinning black hole surrounded by dark matter halo applying the Newman-Janis method and adapting the approach introduced in [63,64].…”

Section: Shadow Of Sgr a * Black Hole Surrounded By Superfluid Dark Mattermentioning

confidence: 99%

Shadows of Sgr A$$^{*}$$ black hole surrounded by superfluid dark matter halo

2020

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In this paper we construct a black hole solution surrounded by superfluid dark matter and baryonic matter, and study their effects on the shadow images of the Sgr A$$^{*}$$∗ black hole. To achieve this goal, we have considered two density profiles for the baryonic matter described by the spherical exponential profile and the power law profile including a special case describing a totally dominated dark matter galaxy. Using the present values for the parameters of the superfluid dark matter and baryonic density profiles for the Sgr A$$^{*}$$∗ black hole, we find that the effects of the superfluid dark matter and baryonic matter on the size of shadows are almost negligible compared to the Kerr vacuum black hole. In addition, we find that by increasing the baryonic mass the shadow size increases considerably. This result can be linked to the matter distribution in the galaxy, namely the baryonic matter is mostly located in the galactic center and, therefore, increasing the baryonic matter can affect the size of black hole shadow compared to the totally dominated dark matter galaxy where we observe an increase of the angular diameter of the Sgr A$$^{*}$$∗ black hole of the magnitude $$10^{-5}\,\upmu $$10-5μarcsec.

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“…There are several examples in the literature where the MNJA was used in order to generate rotating solutions in Boyer-Lindquist-like coordinates (cf., for instance, Refs. [19][20][21][22][23][24][25][26]).…”

Section: Modified Newman-janis Algorithmmentioning

confidence: 99%

Spinning black holes with a separable Hamilton–Jacobi equation from a modified Newman–Janis algorithm

et al. 2020

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Obtaining solutions of the Einstein field equations describing spinning compact bodies is typically challenging. The Newman–Janis algorithm provides a procedure to obtain rotating spacetimes from a static, spherically symmetric, seed metric. It is not guaranteed, however, that the resulting rotating spacetime solves the same field equations as the seed. Moreover, the former may not be circular, and thus expressible in Boyer–Lindquist-like coordinates. Amongst the variations of the original procedure, a modified Newman–Janis algorithm (MNJA) has been proposed that, by construction, originates a circular, spinning spacetime, expressible in Boyer–Lindquist-like coordinates. As a down side, the procedure introduces an ambiguity, that requires extra assumptions on the matter content of the model. In this paper we observe that the rotating spacetimes obtained through the MNJA always admit separability of the Hamilton–Jacobi equation for the case of null geodesics, in which case, moreover, the aforementioned ambiguity has no impact, since it amounts to an overall metric conformal factor. We also show that the Hamilton–Jacobi equation for light rays propagating in a plasma admits separability if the plasma frequency obeys a certain constraint. As an illustration, we compute the shadow and lensing of some spinning black holes obtained by the MNJA.

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Rotating normal and phantom Einstein–Maxwell–dilaton black holes: Geodesic analysis

Abstract: Depending on five parameters, rotating counterparts of Einstein-Maxwell-dilaton black holes are derived. We discuss their physical and geometric properties and investigate their null and time-like geodesics including circular orbits. The Lense-Thirring effect is considered.

Cited by 15 publications

References 58 publications

Shadow and quasinormal modes of a rotating loop quantum black hole

Shadow and quasinormal modes of a rotating loop quantum black hole

Shadows of Sgr A$$^{*}$$ black hole surrounded by superfluid dark matter halo

Spinning black holes with a separable Hamilton–Jacobi equation from a modified Newman–Janis algorithm

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