General Relativity and Gravitation最新文献

Gauge-unfixed Hamiltonian Casimir and static torsionful sector in the Katanaev–Volovich model Katanaev-Volovich模型中的无规hamilton Casimir和静态扭转扇区

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-10-16 DOI: 10.1007/s10714-026-03623-1

Jaime Manuel Cabrera, Jorge Mauricio Paulin Fuentes

{"title":"Gauge-unfixed Hamiltonian Casimir and static torsionful sector in the Katanaev–Volovich model","authors":"Jaime Manuel Cabrera, Jorge Mauricio Paulin Fuentes","doi":"10.1007/s10714-026-03623-1","DOIUrl":"10.1007/s10714-026-03623-1","url":null,"abstract":"<div><p>We give a gauge-unfixed Hamiltonian analysis of the first-order Katanaev–Volovich model of two-dimensional gravity with torsion. The first-order action already singles out natural canonical pairs: the auxiliary Lorentz scalars are conjugate to the spatial connection and zweibein. An extended Dirac–Bergmann embedding isolates an auxiliary second-class sector whose elimination recovers the canonical structure encoded in the first-order action and leaves the first-class constraints generating the local gauge symmetries. An independent Faddeev–Jackiw reduction yields the same reduced brackets. The Katanaev/Poisson–Sigma Casimir is then recovered, up to normalization, directly from the reduced Dirac–Bergmann first-class constraint ideal, before imposing any gauge condition. This identifies the Casimir as a global label of the reduced canonical sectors and supplies a convenient parameter for the torsionful branch. The independent constant normalization of the Killing time is displayed explicitly and then fixed to the local convention <span>(A=1)</span>. In this convention the Casimir-normalized radial field does not coincide with the metric Killing norm: the diagonal representative satisfies <span>(NB=e^{4beta r})</span>. Consequently, torsion modifies the Killing temperature in the chosen Killing-time normalization, while the horizon entropy retains its standard two-dimensional dilaton value and the Casimir-normalized first law holds.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 10","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149189670","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

Unified Ernst potentials formalism for Einstein-Maxwell scalar fields theories 爱因斯坦-麦克斯韦标量场理论的统一恩斯特势形式

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-10-16 DOI: 10.1007/s10714-026-03621-3

Leonel Bixano, Tonatiuh Matos

{"title":"Unified Ernst potentials formalism for Einstein-Maxwell scalar fields theories","authors":"Leonel Bixano, Tonatiuh Matos","doi":"10.1007/s10714-026-03621-3","DOIUrl":"10.1007/s10714-026-03621-3","url":null,"abstract":"<div><p>In the present work, we develop a unified Ernst-type formulation for stationary and axisymmetric Einstein-Maxwell systems coupled to a dilatonic or phantom scalar field, with arbitrary scalar coupling for the Einstein-Maxwell theory. We derive the corresponding five-dimensional potential-space metric and establish an explicit relation between the standard Ernst potentials and the complex one-forms (<i>A</i>, <i>B</i>, <i>C</i>). The degenerate limit <span>(alpha _0=0)</span> is treated separately, distinguishing pure Einstein-Maxwell theory from Einstein-Maxwell gravity coupled to an independent free scalar field. We then project the covariant field equations onto an auxiliary two-dimensional maximally symmetric space with scalar curvature <span>(mathcal {R}_{Sigma }=-8sigma )</span>, and derive the corresponding extended system. Within the non-flat branch and the ansatz considered, we obtain an obstruction to non-constant real scalar configurations in the absence of the electromagnetic sector. The Kerr, Kerr-Newman, Ker-Dilaton in Kaluza-Klein theory, and Bonnor/black-dihole sectors are recovered as consistency checks and applications of the construction. Finally, we introduce a Newman-Penrose-like semi-null coframe for the potential space and compute its connection, curvature forms, and scalar invariants, showing that the target space has constant scalar curvature but is neither conformally flat nor maximally symmetric.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 10","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-026-03621-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149189730","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

Charged Dirac stars 带电狄拉克星

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-10-15 DOI: 10.1007/s10714-026-03614-2

Maribel Hernández-Márquez, Miguel Alcubierre

{"title":"Charged Dirac stars","authors":"Maribel Hernández-Márquez, Miguel Alcubierre","doi":"10.1007/s10714-026-03614-2","DOIUrl":"10.1007/s10714-026-03614-2","url":null,"abstract":"<div><p>In this work we solve the coupled Einstein–Dirac–Maxwell (EDM) system for static spherically symmetric configurations of two fermions in a singlet spinor state within the 3+1 formalism of general relativity. We find different families of stationary self-gravitating solutions for the Dirac field through a numerical shooting method for different values of the electric charge parameter <i>q</i>. Furthermore, we investigate the effect of the charge <i>q</i> on the binding energy, mass, radius, and compactness of the solutions. We show that gravitationally bound configurations exist only for <span>(q<m)</span>, with <i>m</i> the mass of the Dirac field, and that the mass–frequency relation exhibits the characteristic spiral structure previously found for bosonic fields of spin <span>(s=0)</span> and <span>(s=1)</span>. We are able to show that some of these gravitationally bound configurations have a compactness comparable to that of neutron stars. With these results, we conclude that at least at the classical level, self-gravitating fields with different spins <span>(s=0,1/2,1)</span> share some common characteristics when they are coupled to gravity. As has been previously shown for the case of bosonic stars, we also find some super-critical solutions with <i>q</i> slightly larger than <i>m</i>. Such super-critical solutions correspond to configurations such that in the Newtonian regime the Coulomb repulsion overcomes the gravitational attraction, and as such they would not be expected to exist. Nevertheless, even if they do exist in the general relativistic case for a limited range of values of <span>(q>m)</span>, we find that they are always gravitationally unbound.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 10","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-026-03614-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149189654","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

Modified light-cylinder and centrifugal acceleration in Schwarzschild geometry 史瓦西几何中改进的光柱和离心加速度

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-10-13 DOI: 10.1007/s10714-026-03619-x

Nikoloz Kurtskhalia, Nikolai Maltsev, Zaza N. Osmanov

引用次数: 0

Cosmological dynamics of a non-canonical generalised Brans-Dicke theory 非正则广义Brans-Dicke理论的宇宙学动力学

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-10-12 DOI: 10.1007/s10714-026-03616-0

Matthew Debono, Jackson Levi Said, Gabriel Farrugia

{"title":"Cosmological dynamics of a non-canonical generalised Brans-Dicke theory","authors":"Matthew Debono, Jackson Levi Said, Gabriel Farrugia","doi":"10.1007/s10714-026-03616-0","DOIUrl":"10.1007/s10714-026-03616-0","url":null,"abstract":"<div><p>The <span>(Lambda )</span>CDM model has been presented with a number of cosmic tensions in the face of precision cosmological data, suggesting the presence of a dynamical dark energy component. In this context, we investigate the cosmology arising from a generalisation of Brans-Dicke theory, with a non-minimally coupled scalar field characterising deviations from standard general relativity, and having a non-canonical kinetic term. By reformulating the field equations into an autonomous set of dynamical equations, we use the methods of dynamical systems to investigate the equilibrium states of the system and their stability for a set of widely-used potentials, namely the constant, power-law, and exponential potentials, with the flow visualized using bounded phase portraits. Furthermore, we investigate the physical meaning of the critical points, and we find viable solutions that can reproduce the characteristics of the <span>(Lambda )</span>CDM model at background level for each of the three potentials. Furthermore, in each case, we observe that the dynamical behaviour differs noticeably from that observed in other scalar-tensor models due to the non-minimal coupling and non-canonical field, despite using similarly defined dynamical variables.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 10","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-026-03616-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149188991","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

Collective onset of matter-induced scalarization around a black hole with two thin shells 具有两个薄壳的黑洞周围物质诱导的标量化的集体开始

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-10-09 DOI: 10.1007/s10714-026-03620-4

Masahiro Kaminaga

{"title":"Collective onset of matter-induced scalarization around a black hole with two thin shells","authors":"Masahiro Kaminaga","doi":"10.1007/s10714-026-03620-4","DOIUrl":"10.1007/s10714-026-03620-4","url":null,"abstract":"<div><p>We study the linear onset of matter-induced scalarization for a static black hole surrounded by two spatially separated thin matter shells. We assume that the conformal matter coupling is unity on the scalar-free background and that its logarithmic derivative vanishes there. The scalar perturbation then decouples from the metric and matter perturbations at first order, while the invariant surface traces of the shells give singular terms in the scalar equation. For a static spherical black-hole exterior with no bulk scalar effective-mass term between the shells, the onset reduces to the finite-rank condition </p><div><div><span>$$ 1-a_1-a_2+(1-chi )a_1a_2=0, qquad chi =frac{mathcal{S}(R_2)}{mathcal{S}(R_1)}, $$</span></div></div><p>where <span>(a_j)</span> is the attractive strength of shell <i>j</i> normalized by its one-shell threshold on the same background and <span>(mathcal{S})</span> is the static radial resistance. This relation shows that two individually subcritical shells can collectively destabilize the scalar-free black hole. We derive the critical scalar cloud in closed form and verify numerically, in the Schwarzschild probe problem, that a growing mode with a finite growth rate appears beyond the threshold. For an exact scalar-free background consisting of three Schwarzschild regions joined by two Israel shells, we separately derive the static onset condition and the corresponding critical cloud. The exact Israel trace also exhibits a sign transition whose light-shell limit occurs at the Schwarzschild photon sphere.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 10","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-026-03620-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149130527","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

Apparent horizon and causal structure of spacetime singularities 时空奇点的视界和因果结构

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-10-07 DOI: 10.1007/s10714-026-03618-y

Koushiki, Pankaj S. Joshi

引用次数: 0

Two static axisymmetric solutions in Entangled Relativity 纠缠相对论中的两个静态轴对称解

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-10-02 DOI: 10.1007/s10714-026-03615-1

Maxime Wavasseur, Olivier Minazzoli

引用次数: 0

Maxwell–(Lambda (x))-supported regular black holes in unimodular gravity 麦克斯韦- $$Lambda (x)$$在单模重力下支持的规则黑洞

IF 3 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-10-01 DOI: 10.1007/s10714-026-03617-z

G. Alencar

{"title":"Maxwell–(Lambda (x))-supported regular black holes in unimodular gravity","authors":"G. Alencar","doi":"10.1007/s10714-026-03617-z","DOIUrl":"10.1007/s10714-026-03617-z","url":null,"abstract":"<div><p>Recent results [1] show that, when the Einstein Equivalence Principle (EEP) is taken as a fundamental postulate in vacuum, the resulting geometric constraints lead to the condition <span>(g=-1)</span>, corresponding to the spacetime volume element of the Minkowski vacuum. This provides a motivation for considering the unimodular framework, in which the cosmological constant arises as an integration constant in the conservative case and can be generalized to a spacetime-dependent integration function <span>(Lambda (x))</span> when energy–momentum conservation is relaxed. Within this setting, regular black-hole geometries can be supported by significantly simpler matter sources, as part of the effective stress–energy tensor is absorbed into a spacetime-dependent vacuum contribution <span>(Lambda (r))</span>, allowing for Maxwell realizations in a broad class of cases. A global Maxwell description exists if and only if a geometric function <i>H</i>(<i>r</i>) remains non-negative; violations of this condition signal the necessity of a nonlinear electromagnetic sector in part of the spacetime. These results suggest that, within the phenomenological non-conservative unimodular framework considered here, black-hole regularization can be partially reinterpreted as an interplay between the electromagnetic and spacetime-dependent <span>(Lambda (r))</span> sectors.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 10","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-026-03617-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149089607","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

The goldstone bosonic solitons on a cosmic string background 宇宙弦背景下的金石玻色子

IF 2.8 4区物理与天体物理

General Relativity and Gravitation Pub Date : 2026-10-01 DOI: 10.1007/s10714-026-03624-0

F. Ahmadi,Z. Shahbazi,S. Miraboutalebi

引用次数: 0