Shadows of rotating Hayward–de Sitter black holes with astrometric observables

He, Peng-Zhang; Fan, Qi-Qi; Zhang, Haoran; Deng, Jie

doi:10.1140/epjc/s10052-020-08707-z

Cited by 33 publications

(13 citation statements)

References 52 publications

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“…The regular, rotating black holes in, e.g., [31,32,36,[76][77][78][79] can be brought into the form in Eq. ( 13)…”

Section: A Examples Of Spinning Regular Black Holes Included In the H...mentioning

confidence: 99%

Parameterizations of black-hole spacetimes beyond circularity

Delaporte,

Eichhorn,

Held

2022

Preprint

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We discuss parameterizations of black-hole spacetimes in and beyond General Relativity in view of their symmetry constraints: within the class of axisymmetric, stationary spacetimes, we propose a parameterization that includes non-circular spacetimes, both in Boyer-Lindquist as well as in horizon-penetrating coordinates. We show how existing parameterizations, which make additional symmetry assumptions (first, circularity; second, a hidden constant of motion), are included in the new parameterization. Further, we explain why horizon-penetrating coordinates may be more suitable to parameterize non-circular deviations from the Kerr geometry.Our investigation is motivated by our result that the regular, spinning black-hole spacetimes proposed in [1,2] are non-circular. This particular deviation from circularity can result in cusps, a dent and an asymmetry in the photon rings surrounding the black-hole shadow.Finally, we explore a new class of non-circular deviations from Kerr black holes, which promote the spin parameter to a function, and find indications that regularity cannot be achieved in this setting. This result strengthens the case for regular black holes based on a promotion of the mass parameter to a function.

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“…The regular, rotating black holes in, e.g., [31,32,36,[76][77][78][79] can be brought into the form in Eq. ( 13)…”

Section: A Examples Of Spinning Regular Black Holes Included In the H...mentioning

confidence: 99%

Parameterizations of black-hole spacetimes beyond circularity

Delaporte,

Eichhorn,

Held

2022

Preprint

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“…The null geodesic of the Kerr-Newman black hole is properly studied in [7][8][9]. The investigation of null geodesics and the associated optical properties of black holes, such as black hole shadows, have been remain an active topics of research in rotating black hole spacetimes [10][11][12]. The shadow cast by the Schwarzschild black hole was investigated by Synge in 1966 [13].…”

Section: Introductionmentioning

confidence: 99%

Shadow and quasinormal modes of the Kerr–Newman–Kiselev–Letelier black hole

et al. 2022

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We investigate the null geodesics and the shadow cast by the Kerr–Newman–Kiselev–Letelier (KNKL) black hole for the equation of state parameter $$\omega _q=-2/3$$ ω q = - 2 / 3 and for different values of the spacetime parameters, including the quintessence parameter $$\gamma $$ γ , the cloud of string (CS) parameter b, the spin parameter a and the charge Q of the black hole. We notice that for the increasing values of the parameters $$\gamma $$ γ and b the size of the shadow of the KNKL black hole increases and consequently the strength of the gravitational field of the black hole increases. On the other hand with increase in the charge Q of the black hole the size of the shadow of the black hole decreases. Further with the increase in the values of the spin parameter a of the KNKL black hole, we see that the distortion of the shadow of the black hole becomes more prominent. Moreover we use the data released by the Event Horizon Telescope (EHT) collaboration, to restrict the parameters b and $$\gamma $$ γ for the KNKL black hole, using the shadow cast by the KNKL black hole. To this end, we also explore the relation between the typical shadow radius and the equatorial and polar quasinormal mods (QNMs) for the KNKL black hole and extend this correspondence to non-asymptotically flat spacetimes. We also study the emission energy rate from the KNKL black hole for the various spacetime parameters, and observe that it increases for the increasing values of both the parameters $$\gamma $$ γ and b for fixed charge-to-mass and spin-to-mass ratios of the KNKL black hole. Finally, we investigate the effects of plasma on the photon motion, size and shape of the shadow cast by the KNKL black hole. While keeping the spacetime parameters fixed, we notice that with increase in the strength of the plasma medium the size of the shadow of the KNKL black hole decreases and therefore the intensity of the gravitational field of the KNKL black hole decreases in the presence of plasma.

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“…Recently, Chang et al, proposed an approach to describe the size and deformation of shadows using astrophysical observables [32][33][34]. This formalism was used to study the shadow of a rotating Hayward-de Sitter black hole [35].…”

Section: Introductionmentioning

confidence: 99%

Shadow of a nonsingular black hole

Guo¹,

Wei²,

Liu³

2022

Preprint

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Seeking singularity free solutions are important for further understanding black holes in quantum level. Recently, a five-dimensional singularity free topology star/black hole was constructed [Phys. Rev. Lett. 126, 151101 (2021)]. Through the Kaluza-Klein reduction, an effective four-dimensional static spherically symmetric nonsingular black hole can be obtained. In this paper, we study shadow of this nonsingular black hole using three kinds of observers, i.e. static observers, surrounding observers, and freely falling observers, in four-dimensional spacetime. For a spherically symmetric black hole, the shadow is circular for any observer, but the shadow size depends on the motion status of the observer. The shadow size observed by a moving observer will tend to be shrunk. On the other hand, the effect of plasma is also investigated by a simple model. The radius of the photon sphere depends on the plasma model. Most importantly, we find that the shadow sizes do not monotonically decrease with r in some cases. This is a typical phenomenon for this nonsingular black hole.

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Shadows of rotating Hayward–de Sitter black holes with astrometric observables

Cited by 33 publications

References 52 publications

Parameterizations of black-hole spacetimes beyond circularity

Parameterizations of black-hole spacetimes beyond circularity

Shadow and quasinormal modes of the Kerr–Newman–Kiselev–Letelier black hole

Shadow of a nonsingular black hole

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