General Relativity and Gravitation最新文献_第2页

Black hole persistence in scalar-tensor theories 标量张量理论中的黑洞持久性

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-09-19 DOI: 10.1007/s10714-026-03610-6

B. Yildirim, A. A. Coley

{"title":"Black hole persistence in scalar-tensor theories","authors":"B. Yildirim, A. A. Coley","doi":"10.1007/s10714-026-03610-6","DOIUrl":"10.1007/s10714-026-03610-6","url":null,"abstract":"<div><p>We construct a perturbative scalar-tensor solution describing a central inhomogeneity embedded in an evolving cosmological background, with the aim of studying black hole persistence through a nonsingular bounce. Scalar-tensor gravity provides a natural framework for realizing bouncing cosmologies, while the inclusion of a localized inhomogeneity makes the field equations substantially more difficult to solve. We therefore adopt a perturbative scheme, with perturbative parameter <span>(epsilon )</span>, in which the leading-order equations are solved by a spatially flat bouncing FLRW spacetime sourced by a radiation perfect fluid. At next order, a central inhomogeneity is introduced through a generalized McVittie geometry, with the perturbations encoded in the corresponding first-order metric and scalar-field functions. We first allow an anisotropic fluid with radial and tangential pressures, whose diagonal components solve the diagonal field equations. The field equations are solved as a series expansion up to <span>(mathcal {O}(eta ^4))</span> near the bounce at <span>(eta =0)</span>. The resulting perfect fluid solution contains three arbitrary functions which are constrained by requiring the spacetime to asymptote to FLRW as <span>(rrightarrow infty )</span>. With suitable initial conditions preserving the parabolic structure of the bounce, the integration constant <span>(d_0)</span> emerges as the true perturbative parameter: all perturbations vanish as <span>(d_0rightarrow 0)</span>. Finally, we find a small evolving horizon, <span>(r_hsim d_0)</span>, which we interpret as the horizon of the central inhomogeneity. Its persistence through the bounce supports the interpretation of a black hole surviving the cosmological transition, and its evolution is not symmetric about <span>(eta =0)</span>. More precisely, the small branch is a future outer trapping horizon in a two-sided neighbourhood of the bounce; because the construction is local and perturbative, this does not establish the existence of a global event horizon.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149003657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Geodesic congruences and stability of spacetimes with specifically warped extra dimension 具有特殊扭曲额外维度的时空的测地线同余和稳定性

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-09-17 DOI: 10.1007/s10714-026-03612-4

Pabitra Gayen, Ratna Koley

{"title":"Geodesic congruences and stability of spacetimes with specifically warped extra dimension","authors":"Pabitra Gayen, Ratna Koley","doi":"10.1007/s10714-026-03612-4","DOIUrl":"10.1007/s10714-026-03612-4","url":null,"abstract":"<div><p>In this work, we investigate timelike geodesic congruences in the background of two non singular, asymptotically flat spacetimes with a specifically warped extra dimension. The stability of these geometries under the propagation of a massive scalar field is also analyzed. The expansion, shear and rotation (ESR) analysis shows that geodesic congruences are irrotational, with expansion and shear vanishing asymptotically both in the presence and absence of extra-dimensional effect. A detailed study of caustic formation is carried out for both geometries, revealing that the congruences undergo progressive contraction and distortion as they evolve from the asymptotic region toward the caustic. The scalar field experiences a single barrier and a double barrier effective potential in the first and second types of spacetime geometries respectively. In the case of the double barrier potential, multiple reflections of the scalar field between the two peaks give rise to an initial ringdown phase followed by echoes. These echoes gradually decay over time, eventually leading to a late time ringing phase that dominates the signal. The WKB method is employed to compute the quasinormal frequencies (QNFs) for single barrier potentials; however, it is not suitable for the double barrier case. To address this limitation and to validate the WKB results, the Prony fitting method is utilized to determine the QNFs. The influence of various geometric parameters on the QNFs is also examined. The analysis shows that the QNFs possess both real and imaginary components, with the negative imaginary part indicating the stability of the spacetimes under scalar field perturbation.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148986391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Fermionic backreaction on quantum spacetimes: cosmological implications 量子时空上的费米子反作用：宇宙学意义

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-09-16 DOI: 10.1007/s10714-026-03613-3

Y. Tavakoli, A. Khaleghi Ardabili, S. Mosaddegh

{"title":"Fermionic backreaction on quantum spacetimes: cosmological implications","authors":"Y. Tavakoli, A. Khaleghi Ardabili, S. Mosaddegh","doi":"10.1007/s10714-026-03613-3","DOIUrl":"10.1007/s10714-026-03613-3","url":null,"abstract":"<div><p>This article reviews a Hamiltonian framework for describing Dirac fermions propagating on quantum cosmological spacetimes within loop quantum cosmology. Expanding the fermionic field in spinor harmonics on a closed Friedmann–Lemaître–Robertson–Walker background reduces the dynamics to a collection of time-dependent Fermi oscillators, providing a Schrödinger-picture description of fermionic perturbations on a quantum geometry. We discuss the emergence of dressed metrics in the test-field approximation, showing that massive fermions probe both temporal and spatial quantum-geometry corrections, whereas massless fermions, owing to conformal invariance, are affected only through a reparametrization of time. We further review the incorporation of fermionic backreaction within a Born–Oppenheimer framework, where the finite-dimensional Hilbert space of each fermionic mode gives rise to two distinct backreaction channels that naturally generate mode-dependent dressed (rainbow) metrics. Finally, we discuss the cosmological implications of fermionic backreaction, including state-dependent modifications of the quantum bounce and the emergence of an effective cosmological constant in the semiclassical regime. These results highlight the distinctive role of fermionic matter in loop quantum cosmology and outline open directions for understanding quantum fields on quantum spacetimes.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-026-03613-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148986260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Black holes, gravitational waves and space-time singularities (Lemaître Conference 2024) 黑洞、引力波和时空奇点（2024年lema<e:1>会议）

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-09-11 DOI: 10.1007/s10714-026-03608-0

Massimo Bianchi, Sergio Luigi Cacciatori, Matteo Galaverni, Gabriele Gionti S.J., Fabio Scardigli

引用次数: 0

Phase transitions and chaos bound in Horava Lifshitz black holes using Lyapunov exponents 利用Lyapunov指数研究Horava Lifshitz黑洞的相变和混沌界

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-09-10 DOI: 10.1007/s10714-026-03611-5

Mozib Bin Awal, Prabwal Phukon

引用次数: 0

Effective observer-split source terms in rotating frames and gravitomagnetic backgrounds in extended Aharonov-Bohm electrodynamics 扩展Aharonov-Bohm电动力学中旋转框架和重力磁背景下的有效观测器-分裂源项

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-09-10 DOI: 10.1007/s10714-026-03606-2

A. Iadicicco, G. Modanese, L. Verolino

{"title":"Effective observer-split source terms in rotating frames and gravitomagnetic backgrounds in extended Aharonov-Bohm electrodynamics","authors":"A. Iadicicco, G. Modanese, L. Verolino","doi":"10.1007/s10714-026-03606-2","DOIUrl":"10.1007/s10714-026-03606-2","url":null,"abstract":"<div><p>We examine whether the observer split of a covariantly conserved electric current in a rotating finite system can provide a physically constrained effective source for the scalar sector of extended Aharonov–Bohm electrodynamics. We first recall that rotation, a stationary gravitomagnetic background, or a change of coordinates cannot by themselves generate genuine microscopic charge non-conservation for standard locally <i>U</i>(1)-invariant matter; this simple no-go statement is used to delimit the phenomenological. In a <span>(3+1)</span> decomposition adapted to a rotating apparatus, the transport continuity equation contains the exact observer-split term <span>(I_{textrm{split}}=N^{-1}D_i(rho beta ^i))</span>, which reduces for weak rigid rotation to <span>(I_G=Omega partial _phi rho )</span>. We propose to use this restricted, congruence-dependent source as a phenomenological input to the extended scalar sector. The relevant observer/evolution structure is not an arbitrary coordinate choice: the laboratory synchronization and readout protocol select the foliation, while the rotor motion fixes the evolution field relative to it. We characterize which features of a genuine extra-current can and cannot be represented by this construction, and discuss falsifiable signatures, including rotation reversal, axisymmetric-source suppression, gradient scaling, and a recently proposed optically gated rotating-disc test. Analogue-gravity systems are also identified as a possible future setting in which a preferred material flow naturally selects the observer congruence.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-026-03606-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148923304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Failure of local equi-Lipschitzness for families of Lorentz distances to Cauchy surface foliations 柯西面叶理的洛伦兹距离族的局部等lipschitz性失效

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-09-09 DOI: 10.1007/s10714-026-03609-z

Gregory J. Galloway, Robert J. McCann, Argam Ohanyan

引用次数: 0

Rotating regular black hole in a string cloud background: thermodynamics and shadows 弦云背景中旋转的规则黑洞：热力学和阴影

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-09-02 DOI: 10.1007/s10714-026-03598-z

Y. Elaima, H. Lekbich, A. Daassou, F. Oubbad

{"title":"Rotating regular black hole in a string cloud background: thermodynamics and shadows","authors":"Y. Elaima, H. Lekbich, A. Daassou, F. Oubbad","doi":"10.1007/s10714-026-03598-z","DOIUrl":"10.1007/s10714-026-03598-z","url":null,"abstract":"<div><p>We construct and analyze a new stationary axisymmetric black hole solution that describes a regular Kerr spacetime immersed in a string cloud background. By employing the non-complexified Newman-Janis algorithm, we generate a rotating metric from a static seed that incorporates both a regularization parameter <span>(r_0)</span> and a string density parameter <span>(epsilon )</span>. The resulting geometry is regular everywhere, possessing a de Sitter-like core that avoids the central singularity. We investigate the thermodynamic stability of this system, revealing a second-order phase transition and the existence of a thermodynamically stable state where Hawking evaporation ceases. Furthermore, we examine the optical properties of the black hole by modeling its shadow as seen by a distant observer. Our results demonstrate a phenomenological decoupling: while the black hole spin primarily governs the geometric distortion of the shadow, the string cloud density acts as a gravitational magnifying lens, significantly increasing the shadow’s angular diameter.suggesting a phenomenological decoupling that could be tested by future interferometric observations.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148883436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Critical enhancement of Hawking radiation in geometrically deformed dilaton black holes 几何变形膨胀黑洞中霍金辐射的临界增强

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-09-01 DOI: 10.1007/s10714-026-03607-1

Reza Baghbani

{"title":"Critical enhancement of Hawking radiation in geometrically deformed dilaton black holes","authors":"Reza Baghbani","doi":"10.1007/s10714-026-03607-1","DOIUrl":"10.1007/s10714-026-03607-1","url":null,"abstract":"<div><p>We investigate Hawking radiation near the thermodynamic critical point of a four-dimensional dilaton black hole with a geometrically deformed angular sector <span>(R(r)=(r/r_0)^N)</span>. Treating the deformation exponent <i>N</i> as an active control parameter, we locate a second-order phase transition governed by mean-field critical exponents, whose amplitudes are explicitly modulated by <i>N</i>. Solving the Klein–Gordon equation, we derive the exact effective scattering potential and propose a phenomenological Breit–Wigner resonance model for the greybody factor near criticality, motivated by the divergence of thermodynamic response functions. Quasinormal mode analysis in the eikonal limit establishes a correspondence with the unstable photon orbit, and third-order WKB computations of the QNM spectra indicate that <i>N</i> modulates both the ringdown frequency and Lyapunov damping. All thermodynamic, dynamical, and radiative quantities reduce smoothly to the Reissner–Nordström–AdS limit as <span>(N rightarrow 0^-)</span> and <span>(alpha rightarrow 0)</span>. Our results suggest that geometric warping may provide a tunable framework for probing quantum gravitational observables, though direct numerical computation of the greybody factor is required to confirm the predicted resonant enhancement.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148883490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

On non-vacuum black holes in new general relativity 关于新广义相对论中的非真空黑洞

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-09-01 DOI: 10.1007/s10714-026-03605-3

D. F. López, A. A. Coley, B. Yildirim

{"title":"On non-vacuum black holes in new general relativity","authors":"D. F. López, A. A. Coley, B. Yildirim","doi":"10.1007/s10714-026-03605-3","DOIUrl":"10.1007/s10714-026-03605-3","url":null,"abstract":"<div><p>New general relativity (NGR) is a torsion-based modification of general relativity whose Lagrangian depends on three free parameters, <span>((c_{a}, c_{v}, c_{t}))</span>. A subset of the parameter space is physically admissible, namely that which simultaneously ensures ghost-freedom, propagation of a spin-2 mode, and a consistent Newtonian limit. In this work we analyze static and spherically symmetric configurations in NGR, both in vacuum and in the presence of a perfect fluid and an electromagnetic field, under the assumption of the existence of a local black-hole horizon. We find that the mere existence of such configurations forces the free parameters into regions associated with known pathological models: theories that either contain ghost instabilities, do not propagate a spin-2 mode, or lack a Newtonian limit. The remaining geometries are regular at the horizon, so the obstruction is not a breakdown of the geometry but a breakdown of the underlying theory. We therefore conclude that, within the static, spherically symmetric, perturbative framework examined here, NGR does not admit physically meaningful non-trivial black holes distinct from those of the teleparallel equivalent of general relativity.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148883491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0