Shadow Cast of Rotating Charged Black Hole with Scalar Q-Hair

Wu, Meng-He; Guo, Hong; Kuang, Xiao-Mei

doi:10.3390/sym14112237

Cited by 5 publications

(2 citation statements)

References 87 publications

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“…In this paper, in order to obtain a non-circular shadow with distortions, we extend the above metric with m(r) given in Equation (3) to describe a rotating Kerr-like black hole. We employ the Newman-Janis algorithm [47][48][49][50][51][52][53] for a static, spherical regular black hole in Equation (1) and obtain a rotating regular black hole. For a spherical symmetric metric (Equation (1)), we introduce du = dt − dr/ f (r) to find the null coordinates {u, r, θ, φ}.…”

Section: Rotating Kerr-like Regular Black Hole With a Minkowski Corementioning

confidence: 99%

The Shadows of Regular Black Holes with Asymptotic Minkowski Cores

Ling

2022

Symmetry

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We investigate the shadows cast by a sort of new regular black hole which are characterized by an asymptotic Minkowski core and sub-Planckian curvature. First, we extend the metric with spherical symmetry to the one of rotating Kerr-like black holes and derive the null geodesics with a circular orbit near the horizon of the black hole. Then, we plot the shadows of black holes with different values for the deviation parameter. It is found that the size of the shadow shrinks with the increase in the deviation parameter, while the shape of the shadow becomes more deformed. In particular, by comparing with the shadow a Bardeen black hole and Hayward black hole with the same parameter values, we find that, in general, the shadows of black holes with Minkowski cores have larger deformations than those with de Sitter cores, which potentially provides a strategy to distinguish these two sorts of regular black holes with different cores by astronomical observation in the future.

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Section: Rotating Kerr-like Regular Black Hole With a Minkowski Corementioning

confidence: 99%

The Shadows of Regular Black Holes with Asymptotic Minkowski Cores

Ling

2022

Symmetry

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“…Therefore, it serves as a robust tool for estimating black hole parameters [22][23][24][25][26] and for testing GR or its alternatives [27][28][29][30][31][32][33]. Consequently, to probe the nature of black holes, the shadows of different black holes have been studied under various modified theories of gravity [20,26,[34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Properties of Spherically Symmetric Black Holes in the Generalized Brans–Dicke Modified Gravitational Theory

Yang

et al. 2023

Entropy

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The many problems faced by the theory of general relativity (GR) have always motivated us to explore the modified theory of GR. Considering the importance of studying the black hole (BH) entropy and its correction in gravity physics, we study the correction of thermodynamic entropy for a kind of spherically symmetric black hole under the generalized Brans–Dicke (GBD) theory of modified gravity. We derive and calculate the entropy and heat capacity. It is found that when the value of event horizon radius r+ is small, the effect of the entropy-correction term on the entropy is very obvious, while for larger values r+, the contribution of the correction term on entropy can be almost ignored. In addition, we can observe that as the radius of the event horizon increases, the heat capacity of BH in GBD theory will change from a negative value to a positive value, indicating that there is a phase transition in black holes. Given that studying the structure of geodesic lines is important for exploring the physical characteristics of a strong gravitational field, we also investigate the stability of particles’ circular orbits in static spherically symmetric BHs within the framework of GBD theory. Concretely, we analyze the dependence of the innermost stable circular orbit on model parameters. In addition, the geodesic deviation equation is also applied to investigate the stable circular orbit of particles in GBD theory. The conditions for the stability of the BH solution and the limited range of radial coordinates required to achieve stable circular orbit motion are given. Finally, we show the locations of stable circular orbits, and obtain the angular velocity, specific energy, and angular momentum of the particles which move in circular orbits.

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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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Shadow Cast of Rotating Charged Black Hole with Scalar Q-Hair

Cited by 5 publications

References 87 publications

The Shadows of Regular Black Holes with Asymptotic Minkowski Cores

The Shadows of Regular Black Holes with Asymptotic Minkowski Cores

Properties of Spherically Symmetric Black Holes in the Generalized Brans–Dicke Modified Gravitational Theory

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

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