Testing black hole mimickers with the Event Horizon Telescope image of Sagittarius A*

Shaikh, Rajibul

doi:10.1093/mnras/stad1383

Cited by 15 publications

(6 citation statements)

References 75 publications

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“…(4.6), (4.7), (4.10) and (4.11). However, it is also known that the wormhole throat can also act as a location of unstable circular orbits [8,26,[84][85][86]. For such orbits, ∆(r ph ) = 0, and ṙ(r ph ) = 0 is satisfied automatically as rph = r 0 .…”

Section: The Wormhole Casementioning

confidence: 99%

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A rotating modified JNW spacetime as a Kerr black hole mimicker

Pal,

Shaikh

et al. 2023

J. Cosmol. Astropart. Phys.

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The Event Horizon Telescope has recently observed the images and shadows of the compact objects M87* and Sgr A* at the centres of the galaxies Messier 87 and Milky Way. This has opened up a new window in observational astronomy to probe and test gravity and fundamental physics in the strong-field regime. In this paper, we construct a rotating version of a modified Janis-Newman-Winicour metric obtained through the Simpson-Visser regularisation procedure and constrain the metric parameters using the observed shadows of M87* and Sgr A*. Depending on parameter values, the spacetime metric represents either a naked singularity or a wormhole. We find that the naked singularity case is not consistent with observations, as it casts a shadow that is much smaller than the observed ones. On the other hand, the shadow formed by the wormhole branch, depending on the parameter values, is consistent with the observations. We put constraints on the wormhole throat radius by comparing the shadow with the observed ones of M87* and Sgr A*.

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Section: The Wormhole Casementioning

confidence: 99%

“…(4.6), (4.7), (4.10) and (4.11). For more detailed explanation of a shadow in a wormhole case, see [8,26].…”

Section: The Wormhole Casementioning

confidence: 99%

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A rotating modified JNW spacetime as a Kerr black hole mimicker

Pal,

Shaikh

et al. 2023

J. Cosmol. Astropart. Phys.

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“…[ 18,19 ] We can gather data to derive these characteristics by studying black hole shadows, which are essentially dark representations of their event horizon, and photon rings, which are dazzling images formed by photons circling around black holes, [ 20–22 ] which are especially noteworthy since they provide accurate gravity constraints in the strong‐field regime. [ 21,23–53 ] These discrepancies could be caused by many reasons linked with several alternative theories of gravity [ 54–68 ] or the surrounding astrophysical conditions in which the black hole is located. [ 69–76 ] Therefore, it becomes crucial to investigate modified gravity theories and establish constraints by utilizing the black hole's shadow alongside astrophysical data, such as observations from telescopes like EHT.…”

Section: Introductionmentioning

confidence: 99%

Asymptotically‐Flat Black Hole Solutions in Symmergent Gravity

Puliçe,

Pantig,

Övgün

et al. 2024

Fortschritte der Physik

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Symmergent gravity is an emergent gravity model with an curvature sector and an extended particle sector having new particles beyond the known ones. With constant scalar curvature, asymptotically flat black hole solutions are known to have no sensitivity to the quadratic curvature term (coefficient of ). With variable scalar curvature, however, asymptotically‐flat symmergent black hole solutions turn out to explicitly depend on the quadratic curvature term. In the present work, asymptotically‐flat symmergent black holes with variable scalar curvature are constructed and used its evaporation, shadow, and deflection angle to constrain the symmergent gravity parameters. Concerning their evaporation, new particles predicted by symmergent gravity are found, even if they do not interact with the known particles, can enhance the black hole evaporation rate. Concerning their shadow, statistically significant symmergent effects are reached at the level for the observational data of the Event Horizon Telescope (EHT) on the Sagittarius A* supermassive black hole are shown. Concerning their weak deflection angle, discernible features for the boson‐fermion number differences are revealed, particularly at large impact parameters. These findings hold the potential to serve as theoretical predictions for future observations and investigations on black hole properties.

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“…Additionally, recent work by the authors in [22] explored the shadow characteristics of SV black holes/wormholes, establishing meaningful constraints on the parameter l using data from the Event Horizon Telescope (EHT) observations of the M87* and SgrA* supermassive black holes. Their results demonstrated that the SV black hole's shadow closely resembles that of the Kerr black hole.…”

Section: Introductionmentioning

confidence: 99%

Charged Particles Orbiting Charged Black-Bounce Black Holes

Murodov,

Badalov,

Rayimbaev

et al. 2024

Symmetry

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The detailed and comprehensive analysis of radiation processes in accretion disks consisting of electrically charged particles around black holes may provide powerful information about the spacetime geometry of the central black hole. We investigate the circular orbits of electrically charged particles around an electrically charged black-bounce Reissner–Nordström (RN) black hole, known as an RN Simpson–Visser (SV) black hole. We also study the profiles of the innermost stable circular orbits (ISCOs), energy, and angular momentum of the particles in their ISCOs, as well as the efficiency of energy release processes in the accretion disk in the Novikov–Thorne model. Finally, we calculate and study the effects of the black-bounce parameter as well as the black-hole charge on the intensity of the radiation of ultrarelativistic charged particles orbiting the charged RN SV black hole along circular orbits and falling into the black hole. It is observed that the black-bounce parameter essentially decreases the ISCO radius, and consequently the energy extraction and intensity of electromagnetic radiation.

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Testing black hole mimickers with the Event Horizon Telescope image of Sagittarius A*

Cited by 15 publications

References 75 publications

A rotating modified JNW spacetime as a Kerr black hole mimicker

A rotating modified JNW spacetime as a Kerr black hole mimicker

Asymptotically‐Flat Black Hole Solutions in Symmergent Gravity

Charged Particles Orbiting Charged Black-Bounce Black Holes

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