Analytic nondegenerate shift-symmetric Horndeski theories admit no static spherical regular black holes with a time-independent scalar; the unique marginal nonanalytic completion is sGB, whose hairy solutions remain centrally singular.
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Black-bounce to traversable wormhole
Mixed citation behavior. Most common role is background (60%).
abstract
So-called "regular black holes" are a topic currently of considerable interest in the general relativity and astrophysics communities. Herein we investigate a particularly interesting regular black hole spacetime described by the line element \[ ds^{2}=-\left(1-\frac{2m}{\sqrt{r^{2}+a^{2}}}\right)dt^{2}+\frac{dr^{2}}{1-\frac{2m}{\sqrt{r^{2}+a^{2}}}} +\left(r^{2}+a^{2}\right)\left(d\theta^{2}+\sin^{2}\theta \;d\phi^{2}\right). \] This spacetime neatly interpolates between the standard Schwarzschild black hole and the Morris-Thorne traversable wormhole; at intermediate stages passing through a black-bounce (into a future incarnation of the universe), an extremal null-bounce (into a future incarnation of the universe), and a traversable wormhole. As long as the parameter $a$ is non-zero the geometry is everywhere regular, so one has a somewhat unusual form of "regular black hole", where the "origin" $r=0$ can be either spacelike, null, or timelike. Thus this spacetime generalizes and broadens the class of "regular black holes" beyond those usually considered.
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background 5representative citing papers
Unique quasi-topological theories with first-order equations are found for Taub-NUT, NHEK, swirling and related 4D symmetric metrics, enabling closed-form solutions and regular black holes from high-order curvature corrections.
Exact non-singular black holes from the phantom DBI field evaporate to gram-mass relics, opening a new mass window for primordial black holes as dark matter.
A classification of admissible energy density profiles with bounded Kretschmann scalar yields a unified framework for regular static spherically symmetric spacetimes satisfying the weak energy condition, recovering known models and producing new families with hypergeometric and other closed forms.
Dynamical black-hole-to-white-hole transitions require a violation of the null convergence condition for the trapped region to disappear and the anti-trapped region to form.
Exact solutions for asymptotically flat black holes in bumblebee gravity with temporal bumblebee field, analytic Y charge and X potential, and discovery of new cases including unbounded charge-mass ratio and wormhole configurations.
Black-bounce solutions are obtained from a self-interacting 3-form field in GR plus scalar, producing two families that are globally regular with asymmetric horizons and different scalar behaviors.
The paper derives a generalized first law for thin-shell wormholes showing entropy conservation for isolated transparent shells and flux-dependent entropy change when bulk matter crosses the throat.
Regular black-hole and black-bounce solutions are derived in lower-dimensional EGB gravity using nonlinear electrodynamics or unimodular extensions, with thermodynamics showing modified evaporation, remnants, and phase transitions.
Near the wormhole endpoint, the WKB approximation misestimates Hawking luminosities by orders of magnitude; direct numerical greybody factors lengthen an illustrative lifetime estimate by a factor of about 85.
BlackHawk v3.0 adds Hawking temperatures and greybody factors for multiple regular black hole metrics to an existing public code via numerical routines.
Renormalization group improved unimodular black holes with self-consistent radial scale identification yield non-singular metrics and associated mass gaps.
Gravitational tension screening, acting as an analogue of Schwinger corrections, generates regular black bounce spacetimes for spherical, planar, and hyperbolic sections without ad hoc cores.
Combining regular black hole metrics with memory burden suppresses evaporation and opens a 10^6-10^8 g PBH mass window that can comprise all dark matter.
Positive/negative-mass binaries would emit gravitational waves with decreasing frequency and amplitude, and a negative-mass wormhole would cast an asymmetric shadow with richer photon-ring substructure than a black hole.
A regular black hole metric is constructed with sub-Planckian curvature controlled by the inner horizon radius and power-law rather than exponential mass inflation near the inner horizon.
Algebraic equations from Hamiltonian constraints on vacuum spherically symmetric metrics describe non-homogeneous dust collapse and bounce, applied to quantum-inspired models to recover or find new bounce results.
Black bounce geometries exist in 2+1D f(R) gravity with scalar-nonlinear electrodynamics matter, including vanishing scalar curvature solutions whose viability is checked via scalaron mass and energy conditions.
Tidal forces in the Simpson-Visser spacetime produce Roche radii for stars that depend on observer type and regularization, with some disruptions occurring outside the event horizon for supermassive black holes.
Lorentzian-Euclidean black holes produce excess inner-shadow intensity and accumulate energy at the horizon with backreaction unlike stable light rings.
Regular primordial black holes can evaporate completely like singular ones and yield the observed dark matter density under modified cosmological constraints.
Computes quasinormal modes and echoes for black bounce solutions, finding echoes only in certain symmetric horizonless cases and none in asymmetric models that recover Reissner-Nordström externally.
A constructive algorithm yields NEC-obeying static spherical metrics with g_tt g_rr = -1, including a log-corrected Schwarzschild geometry that can mimic black holes.
Unimodular gravity with Maxwell sources yields regular black strings and BTZ black holes supported by a radially varying vacuum energy Λ(r) obtained as an integration constant.
citing papers explorer
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Static regular black holes in Horndeski theories: analytic no-go and nonanalytic obstructions
Analytic nondegenerate shift-symmetric Horndeski theories admit no static spherical regular black holes with a time-independent scalar; the unique marginal nonanalytic completion is sGB, whose hairy solutions remain centrally singular.
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Quasi-topological gravity for 4-dimensional Taub-NUT, near-horizon extreme Kerr, and swirling symmetries
Unique quasi-topological theories with first-order equations are found for Taub-NUT, NHEK, swirling and related 4D symmetric metrics, enabling closed-form solutions and regular black holes from high-order curvature corrections.
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Exact, non-singular black holes from a phantom DBI Field as primordial dark matter
Exact non-singular black holes from the phantom DBI field evaporate to gram-mass relics, opening a new mass window for primordial black holes as dark matter.
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Families of regular spacetimes and energy conditions
A classification of admissible energy density profiles with bounded Kretschmann scalar yields a unified framework for regular static spherically symmetric spacetimes satisfying the weak energy condition, recovering known models and producing new families with hypergeometric and other closed forms.
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Null geodesic defocusing in dynamical black-hole-to-white-hole transitions
Dynamical black-hole-to-white-hole transitions require a violation of the null convergence condition for the trapped region to disappear and the anti-trapped region to form.
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Asymptotically-flat Black holes in Bumblebee gravity: Exact solutions and Thermodynamics
Exact solutions for asymptotically flat black holes in bumblebee gravity with temporal bumblebee field, analytic Y charge and X potential, and discovery of new cases including unbounded charge-mass ratio and wormhole configurations.
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Black Bounce Solutions from a Self-Interacting 3-Form Field in General Relativity
Black-bounce solutions are obtained from a self-interacting 3-form field in GR plus scalar, producing two families that are globally regular with asymmetric horizons and different scalar behaviors.
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Thermodynamics of thin-shell wormholes
The paper derives a generalized first law for thin-shell wormholes showing entropy conservation for isolated transparent shells and flux-dependent entropy change when bulk matter crosses the throat.
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Geometrically Regular Black Object Solutions in Lower-Dimensional Gauss-Bonnet Gravity and Its Unimodular Extension
Regular black-hole and black-bounce solutions are derived in lower-dimensional EGB gravity using nonlinear electrodynamics or unimodular extensions, with thermodynamics showing modified evaporation, remnants, and phase transitions.
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Hawking Emission from Black Holes Evaporating toward Wormholes and the Accuracy of the WKB Approximation
Near the wormhole endpoint, the WKB approximation misestimates Hawking luminosities by orders of magnitude; direct numerical greybody factors lengthen an illustrative lifetime estimate by a factor of about 85.
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$\tt BlackHawk$ $\tt v3.0$: Hawking Radiation from Regular Black Holes
BlackHawk v3.0 adds Hawking temperatures and greybody factors for multiple regular black hole metrics to an existing public code via numerical routines.
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Improved unimodular black holes with self-consistent renormalization scale identification
Renormalization group improved unimodular black holes with self-consistent radial scale identification yield non-singular metrics and associated mass gaps.
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Black Bounce via Gravitational Tension Screening Acting as an Analogue of Schwinger Corrections
Gravitational tension screening, acting as an analogue of Schwinger corrections, generates regular black bounce spacetimes for spherical, planar, and hyperbolic sections without ad hoc cores.
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Memory burden effect of regular primordial black holes
Combining regular black hole metrics with memory burden suppresses evaporation and opens a 10^6-10^8 g PBH mass window that can comprise all dark matter.
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Observational signatures of negative mass wormholes through their shadows
Positive/negative-mass binaries would emit gravitational waves with decreasing frequency and amplitude, and a negative-mass wormhole would cast an asymmetric shadow with richer photon-ring substructure than a black hole.
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Regular black hole with sub-Planckian curvature and suppressed exponential mass inflation
A regular black hole metric is constructed with sub-Planckian curvature controlled by the inner horizon radius and power-law rather than exponential mass inflation near the inner horizon.
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Dust collapse and bounce in spherically symmetric quantum-inspired gravity models
Algebraic equations from Hamiltonian constraints on vacuum spherically symmetric metrics describe non-homogeneous dust collapse and bounce, applied to quantum-inspired models to recover or find new bounce results.
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Three dimensional black bounces in $f(R)$ gravity
Black bounce geometries exist in 2+1D f(R) gravity with scalar-nonlinear electrodynamics matter, including vanishing scalar curvature solutions whose viability is checked via scalaron mass and energy conditions.
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Roche limit and stellar disruption in the Simpson--Visser spacetime
Tidal forces in the Simpson-Visser spacetime produce Roche radii for stars that depend on observer type and regularization, with some disruptions occurring outside the event horizon for supermassive black holes.
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Shadow signatures and energy accumulation in Lorentzian-Euclidean black holes
Lorentzian-Euclidean black holes produce excess inner-shadow intensity and accumulate energy at the horizon with backreaction unlike stable light rings.
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Dark matter production from evaporation of regular primordial black holes
Regular primordial black holes can evaporate completely like singular ones and yield the observed dark matter density under modified cosmological constraints.
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Echoes and quasinormal modes of asymmetric black bounces
Computes quasinormal modes and echoes for black bounce solutions, finding echoes only in certain symmetric horizonless cases and none in asymmetric models that recover Reissner-Nordström externally.
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Energy conditions in static, spherically symmetric spacetimes and effective geometries
A constructive algorithm yields NEC-obeying static spherical metrics with g_tt g_rr = -1, including a log-corrected Schwarzschild geometry that can mimic black holes.
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Regular Black Strings and BTZ Black Hole in Unimodular Gravity Supported by Maxwell Fields
Unimodular gravity with Maxwell sources yields regular black strings and BTZ black holes supported by a radially varying vacuum energy Λ(r) obtained as an integration constant.
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On relativistic observables in black bounce spacetimes
Black bounce spacetimes with larger throat parameter α produce enhanced periastron precession, light deflection, and a larger critical impact parameter in the wormhole regime, offering potential observational signatures.
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Topological Thermodynamics of Generalized Bardeen Black Hole
Generalized Bardeen black holes show two topological defects of opposite winding numbers yielding zero total charge in their thermodynamic vector field, unlike Schwarzschild's single unstable branch, with regularization parameters shaping the phase structure.
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Can wormholes have vanishing Love numbers?
The paper claims the ℓ=2 magnetic tidal Love number of the Dadhich–Kar–Mukherji–Visser R=0 wormhole vanishes to first order in the regularization parameter p, based on a throat-regularity condition that removes the 1/r² response term.
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When Black Holes Can Wear Pants
Theoretical investigation of black hole fragmentation possibilities beyond standard GR constraints, with relevance to primordial black holes and mergers.
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Dymnikova Black Holes in Unimodular Gravity: Maxwell Sources and Vacuum Contributions
Dymnikova black hole geometry is realized via Maxwell sources in unimodular gravity with radially dependent Lambda, producing a regular electric field from a localized charge distribution that has zero net asymptotic charge.