This article was accepted into the corpus but its outbound wikilinks were never NER-processed — typical at the deepest BFS hop or when the run's entity cap was reached. No expansion funnel to show.
| black ring | |
|---|---|
| Name | black ring |
| Caption | Artistic depiction |
| Type | Exotic gravitational solution |
| Discovered by | Roberto Emparan and Harvey Reall |
| Discovery date | 2001 |
| Dimensions | Variable (depends on mass and angular momentum) |
| Location | Higher-dimensional spacetimes |
black ring A black ring is an exact or approximate gravitational solution describing a horizon with ringlike topology in higher-dimensional spacetimes, notable for contrasting with the spherical horizons of Schwarzschild metric and Kerr metric. First constructed in five-dimensional vacuum gravity, black rings exhibit horizon topology S1×S2 and demonstrate non-uniqueness of stationary solutions for given conserved charges such as mass and angular momentum. They play a role in studies connecting General relativity, String theory, Braneworld scenarios, and higher-dimensional black object classifications.
Black rings possess an event horizon with topology S1×S2, yielding properties distinct from spherical black holes like those in the Schwarzschild metric and Myers–Perry metric. Parameters include mass, angular momenta associated with rotations along the S1 and within the S2, and dipole charges when coupled to fields from Kaluza–Klein theory or Supergravity. Thermodynamic characteristics such as horizon area, temperature, and entropy obey generalized laws analogous to the Bekenstein–Hawking entropy relation and the first law of black hole mechanics derived in contexts like Arnowitt–Deser–Misner formalism and the Hamiltonian formulation of general relativity. Stability analyses reference perturbation theory methods used in studies of the Gregory–Laflamme instability and quasinormal mode spectra computed via techniques related to the Teukolsky equation generalizations.
While exact black ring solutions arise in higher-dimensional vacuum and matter-coupled theories, proposals for formation often invoke processes known from gravitational collapse generalized to extra-dimensional settings such as those in Randall–Sundrum models and ADD model. Mechanisms include collapse of rotating matter distributions with sufficient angular momentum to prefer ring topology, fragmentation of higher-dimensional black strings via analogues of the Gregory–Laflamme instability, and mergers in numerical relativity studies inspired by scenarios in AdS/CFT correspondence and brane cosmology. Astrophysical relevance to four-dimensional observations is speculative; however, black ring properties inform possible signatures in high-energy collisions considered in the context of Large Hadron Collider phenomenology and primordial relic scenarios linked to cosmic inflation models involving extra dimensions.
The prototypical black ring solution is the vacuum five-dimensional metric obtained by Roberto Emparan and Harvey Reall using Weyl–Papapetrou techniques adapted to five dimensions. Extensions include charged black rings in U(1) supergravity and dipole rings constructed via solution-generating transformations related to the Belinski–Zakharov transform and hidden symmetries associated with the Geroch group. Families of solutions include thin and fat ring branches distinguished through parameter space studies relying on conserved quantities defined by the Komar integral and asymptotic charges computed via ADM mass prescriptions. Mathematical frameworks for classification draw on topological censorship theorems adapted from work by Stephen Hawking and Gary Gibbons and on uniqueness theorems extended by researchers building on results of David Israel and Werner Israel in higher dimensions.
No direct astrophysical detection of black rings exists; observational prospects depend on evidence for extra dimensions from experiments and cosmological probes such as those conducted by LIGO Scientific Collaboration, Virgo (observatory), and particle detectors at the Large Hadron Collider. Indirect signatures could include atypical gravitational waveforms from higher-dimensional mergers computed using numerical relativity toolkits developed by groups associated with Einstein Toolkit and methods from Post-Newtonian expansion adapted to extra dimensions. In high-energy collisions, hypothetical microscopic black rings might produce distinctive decay patterns predicted in frameworks by Giddings and Thomas or Dimopoulos and Landsberg, constrained by searches reported by collaborations like ATLAS and CMS. Cosmological imprints could be examined through modified background evolution considered in Planck (spacecraft) data analyses and large-scale structure surveys.
Black rings exemplify the breakdown of four-dimensional uniqueness theorems in higher dimensions, challenging extensions of the no-hair theorem and influencing conjectures about the landscape of black objects in string theory and M-theory. They provide testing grounds for ideas in AdS/CFT correspondence by offering geometries dual to thermal states with nontrivial topology, and they connect to microstate counting programs pioneered in contexts involving Strominger–Vafa results and black hole entropy in Type II string theory compactifications. Studies of black ring instabilities inform quantum gravity considerations including holographic thermalization explored by researchers such as Juan Maldacena and Edward Witten.
Related solutions include the black Saturn and di-ring configurations constructed by superposing ring and spherical horizons, studied alongside black string and black brane solutions that arise in Kaluza–Klein theory and Type IIB supergravity. Other variants are supersymmetric black rings preserving fractions of supersymmetry as in work on BPS states and multi-center solutions linked to techniques from Calabi–Yau compactification and algebraic geometry methods used by Michael Green and collaborators. The broader taxonomy of higher-dimensional black objects also contains Myers–Perry black holes, black strings, and black branes, each contributing to a more complete picture of gravitational phenomena beyond four dimensions.
Category:Higher-dimensional black holes