General Relativity and Gravitation最新文献

{"title":"Cosmological study of finite-time singularities under dynamical systems survey in covariant modified teleparallel gravity","authors":"M. G. Ganiou,&nbsp;M. Toure,&nbsp;C. Aïnamon,&nbsp;S. I. V. Hontinfinde,&nbsp;M. J. S. Houndjo","doi":"10.1007/s10714-025-03418-w","DOIUrl":"10.1007/s10714-025-03418-w","url":null,"abstract":"<div><p>In the present study, we deal with the cosmological evolution under autonomous and non-autonomous dynamical systems in the framework of covariant <i>f</i>(<i>T</i>) gravity where <i>T</i> is the scalar torsion. This work first investigates how the dynamical system survey can provide significant explanation near the cosmological finite-time singularities and then extracts the corresponding <i>f</i>(<i>T</i>) models. By studying the de Sitter evolution of the autonomous dynamical system generated from the Friedman equation in a vacuum, we obtain one equilibrium fixed point that describes a universe in accelerated expansion. A similar description is made with finite-time singularity where dynamical systems become necessarily non-autonomous. Near the Big-Rip singularity, an analytical resolution approach leads to finite values for the dynamic variables, which not only reveals an accelerated expanding universe but also makes it possible to reconstruct the corresponding <i>f</i>(<i>T</i>) models. In the case of the three other types of singularity, only type IV leads to an analytical solvable problem, and two of the asymptotic fixed-point coordinates diverge. Furthermore, using a classical approach based on the Hubble parameter of finite-time singularities combined with both Friedman and conservation equations, we provide in the first hand implicit <i>f</i>(<i>T</i>) models for all types of singularity and in the second hand explicit <i>f</i>(<i>T</i>) models whose stability is undertaken near each type of singularity in three different evolutions: de Sitter evolution, quintessence-like evolution, and the phantom-like evolution. The relative stability of the reconstructed models not only shows that they cannot describe all four types of singularity simultaneously but also proves that the cosmological evolution is not the same for the four types of singularity. These results confirm those obtained using the dynamical approach. The finite-time singularity avoidance is discussed at the end of the present investigation.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143979532","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":"Primordial black holes and gravitational waves from inflation","authors":"Misao Sasaki","doi":"10.1007/s10714-025-03412-2","DOIUrl":"10.1007/s10714-025-03412-2","url":null,"abstract":"<div><p>Thanks to the rapid progress in gravitational wave astronomy/cosmology, primordial black holes (PBHs) have become one of the hot topics in cosmology. It has made projections of detecting signatures of PBHs feasible. In parallel, it has become clear that there exist a number of ways to produce PBHs from inflation. In this talk, I will review the PBH formation from inflation and the associated gravitational wave signatures.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03412-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143979528","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":"Nonminimal coupling, quantum scalar field stress-energy tensor and energy conditions on global anti-de Sitter space-time","authors":"Sivakumar Namasivayam,&nbsp;Elizabeth Winstanley","doi":"10.1007/s10714-025-03411-3","DOIUrl":"10.1007/s10714-025-03411-3","url":null,"abstract":"<div><p>We compute the renormalized expectation value of the stress-energy tensor operator for a quantum scalar field propagating on three-dimensional global anti-de Sitter space-time. The scalar field has general mass and nonminimal coupling to the Ricci scalar curvature, and is subject to Dirichlet, Neumann or Robin boundary conditions at the space-time boundary. We consider both vacuum and thermal states, and explore whether the weak and null energy conditions are satisfied by the quantum stress-energy tensor. We uncover a rather complicated picture: compliance with these two energy conditions depends strongly on the mass and coupling of the scalar field to the curvature, and the boundary conditions applied.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03411-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143944232","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":"Entropy correction and quasinormal modes of slowly rotating Kerr–Newman–de Sitter-like black hole in bumblebee gravity","authors":"Ningthoujam Media,&nbsp;Y. Priyobarta Singh,&nbsp;Y. Onika Laxmi,&nbsp;T. Ibungochouba Singh","doi":"10.1007/s10714-025-03414-0","DOIUrl":"10.1007/s10714-025-03414-0","url":null,"abstract":"<div><p>In this paper, we study the tunneling of fermion particle for slowly rotating Kerr–Newman–de Sitter-like (KNdS-like) black hole in bumblebee gravity model by applying the generalized uncertainty principle (GUP). The Hawking temperature of slowly rotating KNdS-like black hole has been modified under GUP. The quantum gravity effect reduces the rise of Hawking temperature of slowly rotating KNdS-like black hole. The modified Hawking temperature and the correction of black hole entropy are investigated by using the tunneling of fermion beyond the semiclassical approximation. We study the scalar field perturbation and effective potential of slowly rotating KNdS-like black hole in bumblebee gravity model by using Klein–Gördon equation. The quasinormal modes for scalar perturbation is investigated using WKB approximation method and Pöschl–Teller fitting method. The significant impact on the greybody factor, Hawking spectra and sparsity of Hawking radiation of the black hole are also studied in the presence of Lorentz violating parameter <i>L</i>.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143932343","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":"Hyperboloidal approach for linear and non-linear wave equations in FLRW spacetimes","authors":"Flavio Rossetti,&nbsp;Alex Vaño-Viñuales","doi":"10.1007/s10714-025-03409-x","DOIUrl":"10.1007/s10714-025-03409-x","url":null,"abstract":"<div><p>In this numerical work, we deal with two distinct problems concerning the propagation of waves in cosmological backgrounds. In both cases, we employ a spacetime foliation given in terms of compactified hyperboloidal slices. These slices intersect <img>\u0000\u0000\u0000\u0000, so our method is well-suited to study the long-time behaviour of waves. Moreover, our construction is adapted to the presence of the time–dependent scale factor that describes the underlying spacetime expansion. First, we investigate decay rates for solutions to the linear wave equation in a large class of expanding FLRW spacetimes, whose non–compact spatial sections have either zero or negative curvature. By means of a hyperboloidal foliation, we provide new numerical evidence for the sharpness of decay–in–time estimates for linear waves propagating in such spacetimes. Then, in the spatially-flat case, we present numerical results in support of small data global existence of solutions to semi-linear wave equations in FLRW spacetimes having a decelerated expansion, provided that a generalized null condition holds. In absence of this null condition and in the specific case of <span>( square _g phi = (partial _t phi )^2 )</span> (Fritz John’s choice), the results we obtain suggest that, when the spacetime expansion is sufficiently slow, solutions diverge in finite time for every choice of initial data.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143932344","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":"Black hole evaporation – 50 years","authors":"William G. Unruh","doi":"10.1007/s10714-025-03391-4","DOIUrl":"10.1007/s10714-025-03391-4","url":null,"abstract":"<div><p>Personal reflections (this is not a scholarly history but my own memories and work on this topic). I apologize beforehand to everyone whose work I do not mention. Note that there is lots of such work, much brilliant. [This document is a transcription of the slides used at the conference, and as a result is rather rough as a document.]</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03391-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143927282","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":"Restricted phase space thermodynamics of dyonic AdS black holes: comparative analysis using different entropy models","authors":"Abhishek Baruah,&nbsp;Prabwal Phukon","doi":"10.1007/s10714-025-03413-1","DOIUrl":"10.1007/s10714-025-03413-1","url":null,"abstract":"<div><p>Using the restricted phase space (RPST) formalism, we perform a comparative study of 4D dyonic AdS black hole thermodynamics in Gibbs–Boltzmann statistics and Rényi statistics. In RPST formalism, instead of pressure and volume, one considers central charge <i>C</i> and chemical potential <span>(mu )</span> as thermodynamic variables. Inclusion of the magnetic charge <span>(tilde{Q}_m)</span> gives rise to a richer phase structure of the study of thermodynamics by adding a non-equilibrium transition from an unstable small black hole to a stable black hole in the <i>T</i>–<i>S</i> processes and a Hawking–Page and Davies type phase transition in the <i>F</i>–<i>T</i> and specific heat plots on top of the Van der Waals and superfluid <span>(lambda )</span> phase transitions. We study an extra mixed ensemble (<span>(tilde{Phi }_e,tilde{Q}_m))</span> due to the inclusion of <span>(tilde{Q}_m)</span> where we see Van der Waals phase transition and whose plots change as the entropy model changes meaning for isovoltage processes we see Hawking–Page transition in Bekenstein–Hawking entropy and absence of Hawking–Page in Rényi entropy construct. We observe an interesting phenomenon where changing the Rényi parameter <span>(lambda )</span>, the <i>T</i>–<i>S</i> process changes the same way as when varying the central charge <i>C</i> underlining some similarity that is not seen in the Bekenstein Hawking entropy model. We observe a similarity between the plots when both charges are turned off relating to the Schwarzschild black hole and the grand-canonical ensemble. One can observe that as the entropy models are changed, the homogeneity is not lost where the mass as a function of extensive variables is of order one and the rest zero. We see a similarity in the <span>(mu )</span>–<i>C</i> process across the entropy models signally some universality across entropy models as well as different types of black holes studied before. Finally, we do not see a new universality class for modified entropy as it is seen in studies done for alternate gravity models.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143902744","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":"Black hole spectroscopy: status report","authors":"Gregorio Carullo","doi":"10.1007/s10714-025-03408-y","DOIUrl":"10.1007/s10714-025-03408-y","url":null,"abstract":"<div><p>A brief overview of the “Black hole spectroscopy program” status is presented. Albeit given from a personal angle, it constitutes an attempt to convey the impressive progress achieved within the field in the last few years. Modeling and observational aspects are touched upon, although both from an observationally-oriented perspective. Particular emphasis is given to recent advancements within general relativity and challenging open problems.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03408-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143884311","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":"Bridging time across null horizons","authors":"Anıl Zenginoğlu","doi":"10.1007/s10714-025-03410-4","DOIUrl":"10.1007/s10714-025-03410-4","url":null,"abstract":"<div><p>General relativity, as a diffeomorphism-invariant theory, allows the description of physical phenomena in a wide variety of coordinate systems. In the presence of boundaries, such as event horizons and null infinity, time coordinates must be carefully adapted to the global causal structure of spacetime to ensure a computationally efficient description. Horizon-penetrating time is used to describe the dynamics of infalling matter and radiation across the event horizon, while hyperboloidal time is used to study the propagation of radiation toward the idealized observer at null infinity. In this paper, we explore the historical and mathematical connection between horizon-penetrating and hyperboloidal time coordinates, arguing that both classes of coordinates are simply regular choices of time across null horizons. We review the height-function formalism in stationary spacetimes, providing examples that may be useful in computations, such as source-adapted foliations or Fefferman–Graham–Bondi coordinates near null infinity. We discuss bridges connecting the boundaries of spacetime through a time hypersurface across null horizons, including the event horizon, null infinity, and the cosmological horizon.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 4","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03410-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143880828","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":"Linear frame dragging along one spatial dimension","authors":"Marco Alberto Javarone,&nbsp;Luciano Pietronero","doi":"10.1007/s10714-025-03407-z","DOIUrl":"10.1007/s10714-025-03407-z","url":null,"abstract":"<div><p>Inertial dragging is a well-known effect described within the framework of General Relativity. Notwithstanding, some fundamental questions related to its nature still deserve attention. One of these, rooted in Mach’s principle, wonders whether the inertial mass of particles could be due to the relative motion with respect to other particles. To tackle this question, we study the inertial dragging resulting in a test particle located in the centre of mass of two faraway masses accelerating in the same direction. In this simple setup, calculations show the appearance of an inertial force, which entails the test particle accelerating in the opposite direction. Therefore, the proposed model shows that relative accelerations of distant masses with respect to a test particle induce inertial dragging effects which are similar to the inertia corresponding to an acceleration of the test particle itself. This could be suggestive of a more concrete interpretation of Mach’s principle which would imply that the gravitational constant may be the approximate value of a more complex inertial field.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 4","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143877900","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}