General Relativity and Gravitation最新文献

{"title":"The space spinor formalism and estimates for spinor fields","authors":"Mariem Magdy,&nbsp;Juan A. Valiente Kroon","doi":"10.1007/s10714-026-03579-2","DOIUrl":"10.1007/s10714-026-03579-2","url":null,"abstract":"<div><p>We show how the space spinor formalism for 2-component spinors can be used to construct estimates for spinor fields satisfying first order equations. We discuss the connection of the approach presented in this article with other strategies for the construction of estimates. In addition, we recast several concepts related to the notion of hyperbolicity in the context of spinor equations. The approach described in this article can be regarded as an adaptation to first order equations of the method of positive commutators for second order hyperbolic equations.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 8","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-026-03579-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148782316","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}

{"title":"A simple pendulum in Schwarzschild spacetime","authors":"Andrzej Czarnecki,&nbsp;Andrew Czezowski","doi":"10.1007/s10714-026-03601-7","DOIUrl":"10.1007/s10714-026-03601-7","url":null,"abstract":"<div><p>We determine the small-oscillation period of a simple pendulum in Schwarzschild spacetime. After transients decay, the displaced rope coincides with a geodesic of the induced spatial metric. This determines the radial lift of the bob to quadratic order in the angular amplitude and leads to the period measured by an observer at the bob’s equilibrium position, <span>(r=r_2)</span>, with the fulcrum at <span>(r_1)</span>, </p><div><div><span>$$ T_{(2)}=4pi frac{r_2^2}{c r_s}sqrt{N_2(N_1-N_2)}, $$</span></div></div><p>where <span>(N_i=N(r_i))</span> and <span>(N(r)=sqrt{1-r_s/r})</span> is the Schwarzschild lapse. The result is therefore expressed in terms of the same function that determines clock rates and gravitational redshifts. In the Newtonian limit, we reproduce the classical result <span>(T=2pi sqrt{L_{0}/g})</span>. We interpret the period close to the horizon in terms of an effective pendulum length. We compare our treatment with the coordinate-length constraint adopted in an earlier study and argue that the two problems are inequivalent away from the classical, weak-field limit.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 8","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148716954","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}

{"title":"Gravitational waves from a binary source in higher dimensional spacetime with compactified extra dimensions","authors":"Mattia Villani","doi":"10.1007/s10714-026-03599-y","DOIUrl":"10.1007/s10714-026-03599-y","url":null,"abstract":"<div><p>We consider the emission of gravitational waves (GW) from a compact binary in a spacetime with compactified extra dimensions. We solve the homogeneous and non-homogeneous wave equation, proving that there is an infinite sum of exponentially decaying pseudo-massive modes which add to the usual one which behaves as 1/<i>r</i> at infinity. We calculate the metric potentials, the equations of motion and the energy flux. We find that in the equations of motion there is a new term at -1PN order. This implies a modification of the energy flux.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 8","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148687925","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}

{"title":"Geometrical and topological aspects of rotating black holes thermodynamics in Lorentz-violating gravity","authors":"Aqsa Mehmood,&nbsp;A. Alkaoud,&nbsp;M. Umair Shahzad,&nbsp;Rafda Rafiq,&nbsp;Abdul Malik Sultan,&nbsp;A. Eid","doi":"10.1007/s10714-026-03597-0","DOIUrl":"10.1007/s10714-026-03597-0","url":null,"abstract":"<div><p>This work investigates the thermodynamic and topological properties of rotating black holes (BHs) in Lorentz-violating gravity. By analyzing the Hawking temperature and heat capacity as functions of the horizon radius, we identify second-order phase transitions and clearly distinguish thermodynamically stable regions from unstable ones. To investigate the critical behavior of the system, several thermodynamic geometry formalisms, such as the Ruppeiner, Hendi–Panahiyan–Eslam Panah–Momennia (HPEM), Weinhold, and Quevedo metrics (Cases I and II) are applied. Our analysis reveals that the scalar curvature of HPEM, Ruppeiner, and Quevedo metrics are in excellent agreement with the zeros of heat capacity and successfully capture the phase transition structure of the BH system. Furthermore, we uncover the topological aspects of BH thermodynamics through phase-space diagrams that expose the existence of non-trivial topological structures. BHs can be interpreted as topological defects in the thermodynamic phase space spanned by variables such as temperature and pressure. One can compute the corresponding winding numbers by exploring these defects at both local and global levels and locate a topological charge that takes discrete values <span>(+1)</span>, 0, or <span>(-1)</span>. Overall, our findings will provide important information about the interplay between thermodynamics, geometry, and topology in rotating BHs within modified gravity theories and may offer valuable constraints on models that incorporate Lorentz symmetry violation.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 8","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148687955","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}

{"title":"Constrained Gauss–Bonnet inflation: analytical predictions, MCMC constraints from Planck/BK18, and primordial black hole signatures","authors":"Feyzollah Younesizadeh,&nbsp;Younes Younesizadeh,&nbsp;Ahmed E. Ali","doi":"10.1007/s10714-026-03596-1","DOIUrl":"10.1007/s10714-026-03596-1","url":null,"abstract":"<div><p>We study a single-field inflationary scenario with a nontrivial coupling to the Gauss–Bonnet term and compute its predictions for the background dynamics and cosmological perturbations. The model is analyzed within the slow-roll regime, and we derive analytic expressions for the inflationary observables, including the scalar spectral index <span>(n_s)</span>, the tensor-to-scalar ratio <i>r</i>, and the running <span>(alpha _s)</span>. Motivated by string-theoretic considerations, we impose the theoretical constraint <span>(V(phi )xi (phi ) = text {constant})</span>, which reduces the parameter space and provides a more predictive framework. The Gauss–Bonnet coupling modifies the standard consistency relations and enables compatibility with current Planck constraints for a broad parameter range (<span>(n_s in [0.955, 0.970])</span>, <span>(r in [0.003, 0.09])</span>). We perform a comprehensive Markov Chain Monte Carlo (MCMC) analysis using Planck 2018 and BICEP/Keck data, obtaining posterior constraints on model parameters. Additionally, we examine swampland compatibility, reheating predictions, non-Gaussian signatures, and potential implications for primordial black hole formation. Our analysis demonstrates that this framework provides a well-motivated extension of standard single-field inflation while maintaining observational viability and offering distinctive testable predictions for future cosmological surveys.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 8","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-026-03596-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148682226","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}

{"title":"Thermodynamics of dynamical black holes beyond perturbation theory","authors":"Abhay Ashtekar,&nbsp;Daniel E. Paraizo,&nbsp;Jonathan Shu","doi":"10.1007/s10714-026-03585-4","DOIUrl":"10.1007/s10714-026-03585-4","url":null,"abstract":"<div><p>The close similarities of the three laws of black hole mechanics, discovered by Bardeen, Carter and Hawking, with the laws of thermodynamics led to the identification of a multiple of the area of the event horizon with entropy. However, developments over the past two decades have shown that this paradigm has some important limitations, especially because of the teleological nature of event horizons. After a brief review of these limitations, we will show that they can be overcome using quasi-local horizons. Specifically, the new first law applies to black holes in general relativity that can be <i>arbitrarily far from equilibrium</i> and refers to <i>finite</i> changes that occur due to <i>physical processes</i> at the horizon. The second law is now a <i>quantitative</i> statement that relates the change in the area of a dynamical horizon segment due to fluxes of energy falling into the black hole. Together, they lead one to identify black hole entropy with the area of marginally trapped surfaces in quasi-local horizons, generalizing recent perturbative findings that it should be identified not with the area of the event horizon but with the area of a marginally trapped surface inside it.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 8","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-026-03585-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148687956","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}

{"title":"The dark sector coupling in anisotropic model: observational aspects and cosmic dynamics","authors":"Ashutosh Singh,&nbsp;Syamala Krishnannair","doi":"10.1007/s10714-026-03595-2","DOIUrl":"10.1007/s10714-026-03595-2","url":null,"abstract":"<div><p>The cosmic dynamics of the interacting dark energy is analyzed in the homogeneous and anisotropic spacetime. In particular, the energy exchange mechanism of the dark sector has been studied with the radiation and baryonic matter in the Bianchi I spacetime. The propagation equations of the expansion and shear scalar have been solved to write the mean Hubble parameter. The posterior phase space of the parameters are portrayed by using the latest supernovae type Ia data from Pantheon+SH0ES sample along with the DESI-BAO, CMB and expansion rate data. It is observed that the parameter space of the interacting models are degenerate in the Bayesian approach based MCMC analysis. However, the joint dataset incorporating CMB data may break this degeneracy. The slowing down of cosmic expansion rate appears to be consistent with the observations. The interacting dark energy may provide a mechanism for the anisotropy dissipation. Furthermore, the interacting dark energy may aid partially in relieving the Hubble tension in these models. However, in these varying dark energy models, the extent of anisotropy may be higher as compared to the constant dark energy density model.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 8","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148612806","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}

{"title":"Horizon data: existence results and a near-horizon equation on general null hypersurfaces","authors":"Miguel Manzano,&nbsp;Marc Mars","doi":"10.1007/s10714-026-03572-9","DOIUrl":"10.1007/s10714-026-03572-9","url":null,"abstract":"<div><p>In a spacetime <span>((mathcal {M},g))</span>, a horizon is a null hypersurface where the deformation tensor <span>(mathcal {K}:=pounds _{eta }g)</span> of a null and tangent vector <span>(eta )</span> satisfies certain restrictions. In this work, we develop a formalism to study the geometry of <i>general</i> horizons (i.e. characterized by any <span>(mathcal {K})</span>), based on encoding the zeroth and first transverse derivatives of <span>(mathcal {K})</span> on null hypersurfaces detached from any ambient spacetime. We introduce the notions of <span>(mathcal {K})</span><i>-tuple</i> and <i>non-isolation tensor</i>. The former encodes the order zero of <span>(mathcal {K})</span>, while the latter is a symmetric 2-covariant tensor that codifies the “degree of isolation\" of a horizon. In particular, the non-isolation tensor vanishes for homothetic, Killing and isolated horizons. As an application we derive a <i>generalized near-horizon equation</i>, i.e., an identity that holds on any horizon (regardless of its topology or whether it contains fixed points), which relates the non-isolation tensor, a certain torsion one-form, and curvature terms. By restricting this equation to a cross-section one can recover the near-horizon equation of isolated horizons and the master equation of multiple Killing horizons. Our formalism allows us to prove two existence theorems for horizons. Specifically, we establish the necessary and sufficient conditions for a non-degenerate totally geodesic horizon with any prescribed non-isolation tensor to be embeddable in a spacetime satisfying any (non-necessarily <span>(Lambda )</span>-vacuum) field equations. We treat first the case of arbitrary topology, and then show how the result can be strengthened when the horizon admits a cross-section.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 8","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-026-03572-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148612807","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}

{"title":"Junction conditions for general gravitational theories","authors":"José M. M. Senovilla","doi":"10.1007/s10714-026-03589-0","DOIUrl":"10.1007/s10714-026-03589-0","url":null,"abstract":"<div><p>The junction conditions for general theories of gravity based on actions that depend on arbitrary functions of the curvature scalar invariants (including differential invariants) are obtained using the distributional formalism. In case of the existence of thin shells, a general expression for the shell energy-momentum tensor is presented. Generalized Israel equations are also obtained. The conditions for a proper matching, without shells, are derived. The main results are: (i) shells arise if the <i>m</i>th-covariant derivative of the Riemann tensor is continuous at the matching hypersurface, where <i>m</i> is the maximum order of differentiation appearing in the Lagrangian density; (ii) a proper junction without thin shells requires further that the <span>((m+1))</span>-th derivative be also continuous, (iii) theories with <span>(m=0)</span> that are quadratic in the scalar curvature invariants are special and unique for they allow for discontinuities of the Riemann tensor resulting in the existence of thin shells and <i>gravitational double layers</i> and (iv) General Relativity and <i>F</i>(<i>R</i>) theories are extraordinary theories that admit shells of curvature (i.e. impulsive gravitational waves) because other theories require the absence of jumps of the second fundamental form across the matching hypersurface. For proper junctions, the continuity across the matching hypersurface of the normal components of the energy-momentum tensor is proven to be a <i>universal</i> property, independently of the field equations, thereby providing important necessary conditions for any matching in any gravitational theory. All results are derived for a minimal coupling with the matter, but the strategy would be analogous for more general couplings.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 8","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-026-03589-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148612810","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}

{"title":"The two-way speed of light in general relativity: conventional and physical content of synchronization","authors":"Paulo Guilherme Santos","doi":"10.1007/s10714-026-03594-3","DOIUrl":"10.1007/s10714-026-03594-3","url":null,"abstract":"<div><p>In special relativity only the two-way (round-trip) speed of light is measurable without a prior synchronization convention; the one-way speed depends on Reichenbach’s parameter <span>(varepsilon in (0,1))</span>, whose value is conventional. We develop the corresponding framework in general relativity, in the threading decomposition of an arbitrary stationary frame. Resynchronizations of the frame’s clocks act as gauge transformations <span>(g_i mapsto g_i + partial _iphi )</span> on the gravitomagnetic potential, leaving the redshift factor <i>h</i> and the radar metric <span>(gamma _{ij})</span> invariant; the one-way speed obeys the exact Reichenbach identity <span>(1/c_+(textbf{n}) + 1/c_+(-textbf{n}) = 2/c)</span>, with synchrony field <span>(varepsilon (x,textbf{n}) = tfrac{1}{2}bigl (1 + sqrt{h},g_i n^ibigr ))</span>; the obstruction to a global Einstein synchronization is the gauge-invariant holonomy <span>(oint g_i,textrm{d}x^i)</span>, realized physically as the Sagnac effect and equivalent to the vorticity of the frame; and slow clock transport carries the same holonomy. Hence the conventional content of one-way light propagation is exactly a gradient, and the triple <span>((h,gamma _{ij},textrm{d}g))</span> exhausts the invariant chronometric content of the frame. We then give the general-relativistic dynamics of the invariants: <span>(textrm{d}g)</span> is the twist of the frame’s Killing congruence; matter and light probe it — never the gauge sector — through an exact gravitomagnetic Lorentz-force law and Fermat’s principle, light rays being the magnetic geodesics of the Randers optical geometry <span>(gamma _{ij}/h)</span>; and the Einstein equations govern it: in vacuo the pair formed by <i>h</i> and the twist potential <span>(chi )</span> obeys the Ernst sigma-model on the radar geometry (for Kerr, <span>(chi = 2macos theta /rho ^2)</span>), while in the weak field mass currents source it. Exact case studies (rotating frames, Schwarzschild, Kerr, the GPS) include the Kerr synchronization holonomy <span>(Delta tau = -8pi ma/bigl (csqrt{r(r-2m)}bigr ))</span> per revolution, of weak-field magnitude <span>(8pi GJ/(c^4 r) approx 1.9times 10^{-16},textrm{s})</span> for Earth-girdling light paths, nine orders of magnitude below the kinematic Sagnac delay corrected for daily by the GPS. Consequences for one-way-speed test theories in gravitational environments are drawn.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"58 8","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148612811","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}