Observational optical constraints of regular black holes

Jafarzade, Khadije; Zangeneh, M. Kord

doi:10.48550/arxiv.2106.13893

Cited by 6 publications

(6 citation statements)

References 58 publications

(66 reference statements)

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“…Moreover, the Event Horizon Telescope has given the angular size of the shadow of M87, which is δ = (42 ± 3)µas. Based on this facts, one has inferred the diameter of the shadow in units of mass M , which is d M 87 = D•δ M ≈ 11 ± 1.5, where D is the distance to M87 [90][91][92]. This means that the diameter of the shadow should be located at the regions 9.5 ∼ 12.5 for 1δ uncertainties and 8 ∼ 14 for 2δ uncertainties.…”

Section: Conclusion and Discussionmentioning

confidence: 98%

Influence of dark matter on shadows and rings of a brane-world black hole illuminated by various accretions

Zeng¹,

He²,

Li³

2021

Preprint

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In this paper, by taking the accretions into account, the observational shadows and rings casted by the Brane-World black hole are numerically investigated when the observer located at the cosmological horizon. The results here show that the radius r p of photon sphere increased with cosmological parameter α and dark matter parameter β, while the impact parameter b p decreased with α and increased with β. For the thin-disk accretion, it turns out that the total observed intensity are mainly composed of the direct emission, while lensing ring and photon ring only contribute a small contribution and a negligible contribution, respectively. And, we find that shadow and rings exhibit some different and interesting features when the disk located at different positions. For the static and infalling spherical accretions, it is obvious that the size of shadow is always the same for both accretions, which means that shadow is only related to the geometry of space time in this case. The luminosity of shadow and photon sphere are closely related to the Doppler effect and the emissivity per unit volume j(ν e ). In addition, the influence of dark matter and cosmological constant on observed intensity of shadows and rings are carefully emphasized throughout of this paper. Finally, we obtained the burring images of shadows and rings by using the nominal resolution of the Event Horizon Telescope, and studied the upper limits on the X-clod dark matter parameter β with the aid of the data of the shadow of M87.

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Section: Conclusion and Discussionmentioning

confidence: 98%

Influence of dark matter on shadows and rings of a brane-world black hole illuminated by various accretions

Zeng¹,

He²,

Li³

2021

Preprint

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show abstract

“…Besides, it should be noted that the Refs. [58,59] are involved in the perturbations of the scalar field or the electromagnetic field on charged black-bounce spacetimes, by using the WKB method, they studied the effects of different spacetimes parameters on the QNMs of the charged black-bounce spacetimes. In our work, by using the time domain integration method, we visually showed the time evolution of scalar field and electromagnetic field in the context of the charged black-bounce spacetimes and studied the ringing of the black hole/wormhole transition, also this transition is characterized by echoes.…”

Section: Discussionmentioning

confidence: 99%

Echoes of charged black-bounce spacetimes

Long

Liu

et al. 2022

Eur. Phys. J. C

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In present work, the evolution of scalar field and electromagnetic field under the background of the charged black-bounce spacetimes are investigated, and we obtain an obvious echoes signal which appropriately reports the properties of the charged black-bounce spacetimes and disclose the physical reasons behind such phenomena. Furthermore, by studying the quasinormal ringdown, we analyze the three states of the charged black-bounce spacetimes in detail, our results show that the echoes signal only appears when $$(|{Q}|\le m)$$ ( | Q | ≤ m ) and $$(|{l}|> m+ \sqrt{m ^{2}-Q^{2} })$$ ( | l | > m + m 2 - Q 2 ) in this spacetime, while when the parameters demand $$(|{Q}|>m)$$ ( | Q | > m ) , the echoes signal will be transformed into a quasinormal ringdown of the two-way traversable wormhole, and the charged black-bounce is a regular black hole with normal horizons by requiring $$(|{Q}|\le m)$$ ( | Q | ≤ m ) and $$(|{l}|< m-\sqrt{m ^{2}-Q^{2} })$$ ( | l | < m - m 2 - Q 2 ) .

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“…the shadow properties, [9][10][11][12][13][14][15][16][17][18][19][20], gravitational lensing [21][22][23][24][25][26][27], accretion disk properties [28][29][30][31][32][33][34][35] and orbital precession [36][37][38][39][40][41][42][43][44]. The similar observable properties were studied in singularity-free compact objects (regular black holes and worm holes) [45][46][47][48][49][50][51][52][53][54][55][56]. The major problem of powering active galactic nuclei, X-ray binaries, and quasars are the most important issues today in high-energy astrophysics.…”

Section: Introductionmentioning

confidence: 99%

Rotational energy extraction from the Kerr black hole's mimickers

Patel¹,

Acharya²,

Bambhaniya³

et al. 2022

Preprint

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In this paper, the Penrose process is being used to extract rotational energy from regular black holes. Initially, we consider the rotating Simpson-Visser regular spacetime which describes the class of geometries of the Kerr black hole's mimickers. The Penrose process is then studied through conformally transformed rotating singular and regular black hole solutions. These both Simpson-Visser and conformally transformed geometries depend on mass, spin, and an additional regularisation parameter l. In both cases, we investigate how the spin and regularisation parameter l affects the configuration of an ergoregion and event horizons. Surprisingly, we find that the energy extraction efficiency from the event horizon surface is not dependent on the regularisation parameter l in the Simpson-Visser regular spacetimes and hence it does not vary from the Kerr black hole case. While, in the conformally transformed singular and regular black holes, we obtain the efficiency rate of extracted energies are extremely high compared to the Kerr black hole scenario. This distinct signature of the conformally transformed singular and regular black holes would be useful to distinguish them from the Kerr black hole in observation.

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Observational optical constraints of regular black holes

Cited by 6 publications

References 58 publications

Influence of dark matter on shadows and rings of a brane-world black hole illuminated by various accretions

Influence of dark matter on shadows and rings of a brane-world black hole illuminated by various accretions

Echoes of charged black-bounce spacetimes

Rotational energy extraction from the Kerr black hole's mimickers

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