Observational and theoretical aspects of Superspinars
arXiv:2407.14851 · doi:10.1007/s10714-025-03383-4
Abstract
This article delves into the observational signatures and theoretical underpinnings of rotating astrophysical objects, with a particular focus on superspinars -exotic objects characterized by the absence of event horizons due to their high angular momentum. While solutions within General Relativity (Kerr superspinars) predict such objects, their classical forms harbor naked singularities, violate causality, and exhibit problematic repulsive gravitational effects. These characteristics render classical superspinars theoretically objectionable, leading to the consideration of them as physically implausible. On the other hand, the incompatibility between General Relativity and Quantum Mechanics suggests the exploration of alternative models, particularly those in which Quantum Gravity dominates the core and prevents the formation of scalar curvature singularities. This work demonstrates that superspinars without scalar curvature singularities can avoid all the complications associated with Kerr superspinars. Moreover, from a phenomenological standpoint, it is shown that the silhouettes of these superspinars could be markedly distinct from those of black holes and classical Kerr superspinars. To substantiate these differences, we perform a comprehensive analysis of inner null geodesics and investigate the structure of the Planckian region within superspinars without scalar curvature singularities. Our study reveals that only these superspinars provide the potential for distant observers to directly observe the extremely high curvature regions within their interiors.
arXiv comment33 pages, 16 figures. In version 2, the article has been revised to align with the published version
References in corpus (40)
- First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
- First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
- Formation and evaporation of non-singular black holes
- Rotating regular black holes
- Shadow of rotating regular black holes
- Prospects for Fundamental Physics with LISA
- Generating rotating regular black hole solutions without complexification
- Apparent shape of super-spinning black holes
- Light rings as observational evidence for event horizons: long-lived modes, ergoregions and nonlinear instabilities of ultracompact objects
- Rotating Regular Black Hole Solution
- Measuring the Kerr spin parameter of regular black holes from their shadow
- Slowly Decaying Waves on Spherically Symmetric Spacetimes and an Instability of Ultracompact Neutron Stars
- A novel family of rotating black hole mimickers
- Appearance of Keplerian discs orbiting Kerr superspinars
- Shapes of rotating nonsingular black hole shadows
- Testing loop quantum gravity from observational consequences of non-singular rotating black holes
- Regular rotating electrically charged black holes and solitons in nonlinear electrodynamics minimally coupled to gravity
- "Kerrr" black hole: the Lord of the String
- Astrophysical Violations of the Kerr Bound as a Possible Signature of String Theory
- Asymptotic safety casts its shadow
- Gravitational instabilities of superspinars
- Quantum Gravity Effects in the Kerr Spacetime
- Spacetime completeness of non-singular black holes in conformal gravity
- Spinning Loop Black Holes
- Quest for realistic non-singular black-hole geometries: Regular-center type
- Imaging a non-singular rotating black hole at the center of the Galaxy
- Photon ring structure of rotating regular black holes and no-horizon spacetimes
- From a locality-principle for new physics to image features of regular spinning black holes with disks
- On regular rotating black holes
- Zero mass limit of Kerr spacetime is a wormhole
- From regular black holes to horizonless objects: quasi-normal modes, instabilities and spectroscopy
- Destroying the event horizon of a nonsingular rotating quantum-corrected black hole
- Quantum gravity lights up spinning black holes
- Non-singular quantum improved rotating black holes and their maximal extension
- On the stability of a superspinar
- Regular Rotating Black Holes: A Review
- On the nature of inner light-rings
- Instability of a Kerr-type naked singularity due to light and matter accretion and its shadow
- The Interiors of Singularity-Free Rotating Black Holes
- Super black hole as spinning particle: Supersymmetric baglike core