Shapes of rotating nonsingular black hole shadows

Amir, M. Jamil; Ghosh, Sushant G.

doi:10.1103/physrevd.94.024054

Cited by 152 publications

(98 citation statements)

References 74 publications

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“…If we combine Eqs. (25) and (27), we see that the temperature of the envelope of debris goes to zero as µ 1/4 . This makes harder to probe this phenomenon the more compact the CMO is.…”

Section: Infalling Matter Close To the Gravitational Radiusmentioning

confidence: 65%

“…These are rather limited if the model breaks down at a late stage of the evaporation process, where significant deviations from classical black hole dynamics are expected to arise. The only possibility is to consider the deviations from the Schwarzschild geometry in the near-horizon region or even outside the black hole, and check how these modifications affect physical processes (e.g., [24][25][26]) that take place in these regions during periods of time which are much smaller than the typical timescale for the dynamical evolution of the regular black hole itself. From Eq.…”

Section: A Regular Black Holesmentioning

confidence: 99%

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Phenomenological aspects of black holes beyond general relativity

et al. 2018

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While singularities are inevitable in the classical theory of general relativity, it is commonly believed that they will not be present when quantum gravity effects are taken into account in a consistent framework. In particular, the structure of black holes should be modified in frameworks beyond general relativity that aim at regularizing singularities. Being agnostic on the nature of such theory, in this paper we classify the possible alternatives to classical black holes and provide a minimal set of phenomenological parameters that describe their characteristic features. The introduction of these parameters allows us to study, in a largely model-independent manner and taking into account all the relevant physics, the phenomenology associated with these quantummodified black holes. We perform an extensive analysis of different observational channels and obtain the most accurate characterization of the viable constraints that can be placed using current data. Aside from facilitating a critical revision of previous work, this analysis also allows us to highlight how different channels are capable of probing certain features but are oblivious to others, and pinpoint the theoretical aspects that should be addressed in order to strengthen these tests.

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“…If we combine Eqs. (25) and (27), we see that the temperature of the envelope of debris goes to zero as µ 1/4 . This makes harder to probe this phenomenon the more compact the CMO is.…”

Section: Infalling Matter Close To the Gravitational Radiusmentioning

confidence: 65%

Section: A Regular Black Holesmentioning

confidence: 99%

Phenomenological aspects of black holes beyond general relativity

et al. 2018

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“…Further, the shadows of super-extremal Kerr black holes [16] and Kerr-Newman-NUT spacetimes [83] as well as Kerr black holes with scalar hair [46,142] have been explored. Regular spacetimes have been studied in [3,9,133,138]. The shadow of non-commutative-geometry inspired black-hole spacetimes has been investigated in [147].…”

Section: Motivationmentioning

confidence: 99%

Asymptotic safety casts its shadow

Held

Gold

Eichhorn

2019

J. Cosmol. Astropart. Phys.

113

138

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We set out to bridge the gap between regular black-hole spacetimes and observations of a black-hole shadow by the Event Horizon Telescope. We explore modifications of spinning and non-spinning black-hole spacetimes inspired by asymptotically safe quantum gravity which features a scale dependence of the Newton coupling. As a consequence, the predictions of our model, such as the shadow shape and size, depend on one free parameter determining the curvature scale at which deviations from General Relativity set in. In more general new-physics settings, it can also depart substantially from the Planck scale. In this case, the free parameter is constrained by observations, since the corresponding curvature scale is significantly below the Planck-scale. The leading new-physics effect can be recast as a scale-dependent black-hole mass, resulting in distinct observational signatures of our model. As a concrete example, we show that two mass-measurements, extracted from the size of the shadow and from Keplerian orbital motion of stars, allow to distinguish the classical from the modified, regular black-hole spacetime, yielding a bound on the free parameter. For spinning black holes, we further find that the singularity-resolving new physics puts a characteristic dent in the shadow. Finally, we argue, based on the underlying physical mechanism, that the effects we derive could be generic consequences of a large class of quantum-gravity theories.

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“…We have interpolated the numerical values of observables from integrals Eqs. (22), (23), and using Eq. (24) to approximate these observables by polynomials in terms of black hole parameters.…”

mentioning

confidence: 99%

Black Hole Parameter Estimation from Its Shadow

Kumar

Ghosh

2020

ApJ

Self Cite

165

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The shadow (image) of a black hole, Sgr A* in the center of Milky-Way, can be important observational evidence for an existence of a black hole that is likely to be captured by the Event Horizon Telescope. This would provide with direct observations the black hole existence as well as to understand gravity in the most extreme region near the event horizon, and also helps to conclude if the general relativity agrees to the observation. Is it possible to estimate the black hole parameters by observation of shadow? To answer this, we present general observables, namely, area (A) and circumference (C) expressed in terms of ordinary integrals characterizing the apparent shadow shape. More precisely, we estimate parameters associated with different black holes, viz., Kerr, Kerr-Newman and rotating regular black holes, and then compare with existing results from other methods. We find that our method is accurate and in accordance with the existing results.Our formalism does not approximate the apparent shadow by a reference circle and is applicable to any kind of shape.

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Shapes of rotating nonsingular black hole shadows

Cited by 152 publications

References 74 publications

Phenomenological aspects of black holes beyond general relativity

Phenomenological aspects of black holes beyond general relativity

Asymptotic safety casts its shadow

Black Hole Parameter Estimation from Its Shadow

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