Signatures of regular black holes from the shadow of Sgr A* and M87*

Banerjee, Indrani; Sau, Subhadip; SenGupta, Soumitra

doi:10.1088/1475-7516/2022/09/066

Cited by 13 publications

(5 citation statements)

References 107 publications

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“…As a result, the Sgr A * black hole shadow is consistent with the Ghosh-Culetu black holes and not with the corresponding no-horizon spacetimes. Recently, constraints on the Ghosh-Culetu black hole parameters have been derived from the angular diameter of the shadow of the Sgr A * black hole (Banerjee et al 2022).…”

Section: Observational Constraints From the Eht Results Ofmentioning

confidence: 99%

Testing Rotating Regular Metrics with EHT Results of Sgr A*

Kumar

Ghosh

Maharaj

2022

ApJ

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The Event Horizon Telescope (EHT) observation unveiled the first image of supermassive black hole Sgr A* showing a shadow of diameter θ sh = 48.7 ± 7 μas with fractional deviation from the Schwarzschild black hole shadow diameter δ = − 0.08 − 0.09 + 0.09 ( VLTI ) , − 0.04 − 0.10 + 0.09 ( Keck ) . The Sgr A* shadow size is within 10% of the Kerr predictions, providing us with another tool to investigate the nature of strong-field gravity. We use the Sgr A* shadow observables to constrain metrics of four independent and well-motivated, parametrically different from Kerr spacetime, rotating regular spacetimes and the corresponding no-horizon spacetimes. We present constraints on the deviation parameter g of rotating regular black holes. The shadow angular diameter θ sh within the 1σ region places bounds on the parameters a and g. Together with EHT bounds on the θ sh and δ of Sgr A*, our analysis concludes that the three rotating regular black holes, i.e., Bardeen, Hayward, and Simpson–Visser black holes, and corresponding no-horizon spacetimes agree with the EHT results of Sgr A*. Thus, these three rotating regular spacetimes and Kerr black holes are indiscernible in some parameter space, and one cannot rule out the possibility of the former being strong candidates to be astrophysical black holes.

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Section: Observational Constraints From the Eht Results Ofmentioning

confidence: 99%

Testing Rotating Regular Metrics with EHT Results of Sgr A*

Kumar

Ghosh

Maharaj

2022

ApJ

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“…The traditional regular black holes can be viewed as solutions of gravity coupled to nonlinear electrodynamics [57][58][59], and the parameter g in this paper may be viewed as the charge of the nonlinear electromagnetic field. Just as the increase in charge made the size of the black hole horizon smaller, the corresponding size of the shadow shrank, while the shape of the shadow became more deformed [32,45,60]. Furthermore, we compared the shadows for two different types of regular black holes with the same parameter values.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…Therefore, investigating the shadows of regular black holes theoretically, as performed in this manuscript, could shed light on this issue and improve our understanding of the observation data of detected black holes. Previously, the shadows of regular black holes with de Sitter cores were investigated in [30], and the study of shadows has also been extended to regular black holes with Minkowski cores [43][44][45]. However, the black holes with Minkowski cores previously studied in the literature have a shortcoming.…”

Section: Introductionmentioning

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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“…The spatial angular resolution of VLBI radio observation is now below the horizon radius of supermassive black holes viz. Sgr A * and M87 [50][51][52][53][54][55][56][57][58]. This has opened up the possibility of determination of the parameters of the astrophysical black holes using black hole shadows [59][60][61][62][63].…”

Section: Introductionmentioning

confidence: 99%

Parameter estimation of the Bardeen-Kerr black hole in cloud of strings using shadow analysis

Kumar Vishvakarma,

Veer Singh,

Siwach

2024

Phys. Scr.

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We consider the rotating generalization of the Bardeen black hole solution in the presence of cloud of strings (CoS). The parameter space for which the black hole horizon exists is determined. We also study the static limit surface and the ergo-region in the presence of the CoS parameter. We consider photon orbits and obtain the deformation of black hole shadows due to rotation for various values of the CoS parameter. The shadow deformation is used to determine the black hole spin for different values of the black hole parameters.

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Signatures of regular black holes from the shadow of Sgr A* and M87*

Cited by 13 publications

References 107 publications

Testing Rotating Regular Metrics with EHT Results of Sgr A*

Testing Rotating Regular Metrics with EHT Results of Sgr A*

The Shadows of Regular Black Holes with Asymptotic Minkowski Cores

Parameter estimation of the Bardeen-Kerr black hole in cloud of strings using shadow analysis

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