A no-go theorem for regular black holes

Chinaglia, Stefano

doi:10.48550/arxiv.1805.03899

Cited by 4 publications

(4 citation statements)

References 23 publications

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“…The essential difference is that, in our case, the outermost surface of the collapsing matter reaches the Schwarzschild radius before stabilizing. Our model is also consistent with the recent discussion in [27].…”

Section: Introductionsupporting

confidence: 93%

Resisting collapse: How matter inside a black hole can withstand gravity

Brustein

Medved

2019

Phys. Rev. D

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How can a Schwarzschild-sized matter system avoid a fate of gravitational collapse?To address this question, we critically reexamine the arguments that led to the "Buchdahl bound", which implies that the minimal size of a stable, compact object must be larger than nine eighths of its own Schwarzschild radius. Following Mazur and Mottola, and in line with other counterexamples to the singularity theorems, we identify large negative radial pressure extending to the gravitational radius as the essential ingredient for evading the Buchdahl bound. Our results are novel although consistent with many other investigations of models of non-singular black holes. It is shown in particular that a large negative pressure in the framework of classical GR translates into a large positive pressure once quantum physics is incorporated. In this way, a Schwarzschild-sized bound state of closed, interacting fundamental strings in its high-temperature Hagedorn phase can appear to have negative pressure and thus the ability to resist gravitational collapse.

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Section: Introductionsupporting

confidence: 93%

Resisting collapse: How matter inside a black hole can withstand gravity

Brustein

Medved

2019

Phys. Rev. D

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“…To the best of our knowledge, [1065] was the first to introduce the non-polynomial gravity approach. Models of these type have later been considered in various works (particularly in the search for regular BHs), see for instance [1066][1067][1068][1069][1070][1071][1072][1073][1074][1075].…”

Section: Dst Black Holementioning

confidence: 99%

Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A ∗

Vagnozzi

Roy

Tsai

et al. 2023

Class. Quantum Grav.

220

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Horizon-scale images of black holes (BHs) and their shadows have opened an unprecedented window onto tests of gravity and fundamental physics in the strong-field regime. We consider a wide range of well-motivated deviations from classical General Relativity (GR) BH solutions, and constrain them using the Event Horizon Telescope (EHT) observations of Sagittarius A* (Sgr A*), connecting the size of the bright ring of emission to that of the underlying BH shadow and exploiting high-precision measurements of Sgr A*’s mass-to-distance ratio. The scenarios we consider, and whose fundamental parameters we constrain, include various regular BHs, string-inspired space-times, violations of the no-hair theorem driven by additional fields, alternative theories of gravity, novel fundamental physics frameworks, and BH mimickers including well-motivated wormhole and naked singularity space-times. We demonstrate that the EHT image of Sgr A* places particularly stringent constraints on models predicting a shadow size larger than that of a Schwarzschild BH of a given mass, with the resulting limits in some cases surpassing cosmological ones. Our results are among the first tests of fundamental physics from the shadow of Sgr A* and, while the latter appears to be in excellent agreement with the predictions of GR, we have shown that a number of well-motivated alternative scenarios, including BH mimickers, are far from being ruled out at present.

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“…Therefore, a non-singular black hole is not a generic configuration and the criterion C5 in Section 1 is not fulfilled in the system (2.45). This property has been studied in a more general framework in [63].…”

Section: Nonlinear Electromagnetic Fieldmentioning

confidence: 99%

Quest for realistic non-singular black-hole geometries: Regular-center type

Maeda¹

2021

Preprint

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We propose seven criteria to single out physically reasonable non-singular black-hole models and adopt them to four different spherically symmetric models with a regular center and their rotating counterparts. In general relativity, all such non-singular black holes are non-generic with a certain matter field including a class of nonlinear electromagnetic fields. According to a criterion that the effective energy-momentum tensor should satisfy all the standard energy conditions in asymptotically flat regions, the well-known Bardeen and Hayward black holes are discarded. In contrast, the Dymnikova and Fan-Wang black holes respect the dominant energy condition everywhere. Although the rotating Fan-Wang black hole contains a curvature singularity, the rotating Dymnikova black hole is free from scalar polynomial curvature singularities and closed timelike curves. In addition, the dominant energy condition is respected on and outside the event horizons in the latter case. The absence of parallelly propagated curvature singularities remains an open question.

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A no-go theorem for regular black holes

Cited by 4 publications

References 23 publications

Resisting collapse: How matter inside a black hole can withstand gravity

Resisting collapse: How matter inside a black hole can withstand gravity

Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A ∗

Quest for realistic non-singular black-hole geometries: Regular-center type

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