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General Relativity and Gravitation最新文献

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Influence of the cosmological constant on (kappa )-deformed neutron star 宇宙常数对变形中子星的影响
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2024-08-08 DOI: 10.1007/s10714-024-03279-9
R. Bhagya, Diganta Parai, Harsha Sreekumar, Suman Kumar Panja
{"title":"Influence of the cosmological constant on (kappa )-deformed neutron star","authors":"R. Bhagya,&nbsp;Diganta Parai,&nbsp;Harsha Sreekumar,&nbsp;Suman Kumar Panja","doi":"10.1007/s10714-024-03279-9","DOIUrl":"10.1007/s10714-024-03279-9","url":null,"abstract":"<div><p>We study a model of the neutron star in <span>(kappa )</span>-deformed space-time in the presence of the cosmological constant (<span>(Lambda )</span>). The Einstein tensor and the energy-momentum tensor are generalized to <span>(kappa )</span>-deformed space-time and we construct the field equations with the cosmological constant. Considering the interior of the star to be a perfect fluid as in the commutative case, we find the Tolman–Oppenheimer–Volkoff equations with the inclusion of the cosmological constant in <span>(kappa )</span>-deformed space-time. The behavior of the maximum allowed mass of the star and its radius are studied with the variation in the cosmological constant as well as the deformation parameter. We see that the non-commutativity enhances the mass of the star and its maximum mass increases with a decrease in the cosmological constant. The maximum mass varies from 3.44 to <span>(3.68,text {M}_{odot })</span> as <span>(Lambda )</span> varies from <span>(10^{-10})</span> to <span>(10^{-15},text {m}^{-2})</span>. We also obtain the compactness factor and surface redshift of the star. We observe that the compactness of the star increases as the cosmological constant decreases, whereas the surface redshift of the star decreases with a decrease in the cosmological constant. The compactness factor and surface redshift corresponding to the maximum mass of the neutron star remains almost constant as <span>(Lambda )</span> decreases.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"56 8","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141909165","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
Localized chaos due to rotating shock waves in Kerr–AdS black holes and their ultraspinning version 克尔-AdS黑洞旋转冲击波引起的局部混沌及其超旋版本
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2024-07-29 DOI: 10.1007/s10714-024-03275-z
Hadyan Luthfan Prihadi, Freddy Permana Zen, Donny Dwiputra, Seramika Ariwahjoedi
{"title":"Localized chaos due to rotating shock waves in Kerr–AdS black holes and their ultraspinning version","authors":"Hadyan Luthfan Prihadi,&nbsp;Freddy Permana Zen,&nbsp;Donny Dwiputra,&nbsp;Seramika Ariwahjoedi","doi":"10.1007/s10714-024-03275-z","DOIUrl":"10.1007/s10714-024-03275-z","url":null,"abstract":"<div><p>The butterfly velocity of four-dimensional rotating charged asymptotically AdS black hole is calculated to probe chaos using localized rotating shock waves. In this work, we obtain the angular momentum dependence of the butterfly velocity due to rotation in the shock wave probes. In general, the angular momentum <span>(mathcal {L})</span> of the shock waves increases the butterfly velocity. The localized shocks also generate butterfly velocities which vanish when we approach extremality, indicating no entanglement spread near extremality. One of the butterfly velocity modes is well bounded by both the speed of light and the Schwarzschild-AdS result, while the other may become superluminal. Aside from the logarithmic behavior of the scrambling time which indicates chaos, the Lyapunov exponent is also positive and bounded by <span>(kappa =2pi T_H/(1-mu mathcal {L}))</span>. The Kerr–NUT–AdS and Kerr–Sen–AdS solutions and their ultraspinning versions are used as examples to attain a better understanding of the chaotic phenomena in rotating black holes, especially those with extra conserved charges.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"56 8","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141791043","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
Elementary considerations on gravitational waves from hyperbolic encounters 关于双曲遭遇引力波的基本考虑
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2024-07-27 DOI: 10.1007/s10714-024-03276-y
Martin Teuscher, Aurélien Barrau, Killian Martineau
{"title":"Elementary considerations on gravitational waves from hyperbolic encounters","authors":"Martin Teuscher,&nbsp;Aurélien Barrau,&nbsp;Killian Martineau","doi":"10.1007/s10714-024-03276-y","DOIUrl":"10.1007/s10714-024-03276-y","url":null,"abstract":"<div><p>We examine the main properties of gravitational waves (GWs) emitted by transient hyperbolic encounters of black holes. We begin by building the set of basic variables most relevant to setting our problem. After exposing the ranges of masses and eccentricities accessible at a given GW frequency, we analyze the dependence of the gravitational strain on those parameters and determine the trajectories resulting in the most sizeable strains. Some non-trivial behaviors are unveiled, showing that highly eccentric events can be more easily detectable than parabolic ones. In particular, we underline the correct way to extend formulas from hyperbolic to parabolic orbits. Our reasonings are as general as possible, and we make a point of explaining our considerations pedagogically. The majority of the work is based on Newtonian dynamics and aims at being a benchmark to which more accurate calculations can be compared.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"56 8","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141768452","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
Approximating photon trajectories in spherically symmetric spacetimes 球对称时空中的光子轨迹近似图
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2024-07-24 DOI: 10.1007/s10714-024-03274-0
Joseph Sultana
{"title":"Approximating photon trajectories in spherically symmetric spacetimes","authors":"Joseph Sultana","doi":"10.1007/s10714-024-03274-0","DOIUrl":"10.1007/s10714-024-03274-0","url":null,"abstract":"<div><p>In this paper we use the Homotopy analysis method to obtain an analytic approximation for the entire photon trajectory in the Schwarzschild spacetime. This is usually expressed exactly in terms of an elliptic integral. We compare our approximation with other formulae found in the literature, which were specifically obtained for the Schwarzschild solution. Unlike some of these formulae, our approximation can be applied and maintains a good accuracy for emission point close to the event horizon and also for emission angles close to and greater than <span>(pi /2)</span>. We show that our method can easily be applied to other spherically symmetric solutions such as the Reissner-Nordström solution. Such an approximation would be useful when accurate determination of the light trajectories around compact objects is required without the need to revert to time consuming numerical integration of elliptic integrals.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"56 8","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-024-03274-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141764040","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
Exponential correction to Friedmann equations 弗里德曼方程的指数修正
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2024-07-18 DOI: 10.1007/s10714-024-03273-1
Özgür Ökcü, Ekrem Aydiner
{"title":"Exponential correction to Friedmann equations","authors":"Özgür Ökcü,&nbsp;Ekrem Aydiner","doi":"10.1007/s10714-024-03273-1","DOIUrl":"10.1007/s10714-024-03273-1","url":null,"abstract":"<div><p>In this paper, employing the exponential corrected entropy (Chatterjee and Ghosh in Phys Rev Lett 125:041302, 2020), we derive the modified Friedmann equations from the first law of thermodynamics at apparent horizon and Verlinde’s entropic gravity scenario. First, we derive the modified Friedmann equations from the first law of thermodynamics. We investigate the validity of generalised second law (GSL) of thermodynamics and find that it is always satisfied for the all eras of universe. Moreover, we investigate the deceleration parameter for the case <span>(k=0)</span> in two frameworks. Finally, we numerically study the bouncing behaviour for the modified Friedmann equations obtained from entropic gravity. The results indicate that the bouncing behaviour is possible for the cases <span>(k=1)</span> and <span>(k=-1)</span>.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"56 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-024-03273-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141726032","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
Some remarks on Bardeen-AdS black hole surrounded by a fluid of strings 关于被弦流体包围的巴丁-AdS 黑洞的几点评论
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2024-07-12 DOI: 10.1007/s10714-024-03268-y
F. F. Nascimento, Pedro H. Morais, J. M. Toledo, V. B. Bezerra
{"title":"Some remarks on Bardeen-AdS black hole surrounded by a fluid of strings","authors":"F. F. Nascimento,&nbsp;Pedro H. Morais,&nbsp;J. M. Toledo,&nbsp;V. B. Bezerra","doi":"10.1007/s10714-024-03268-y","DOIUrl":"10.1007/s10714-024-03268-y","url":null,"abstract":"<div><p>We obtain a class of solutions that correspond to a generalization of the Bardeen black hole solution by solving the Einstein equations coupled to a particular nonlinear electromagnetic field. The generalization is realized by considering, additionally, the presence of the cosmological constant and a source corresponding to an anisotropic fluid, namely, a fluid of strings, which surrounds the black hole. We show that the obtained class of solutions preserve or not the regularity of the original Bardeen black hole solution, depending on the values of the parameter <span>(beta )</span> which labels the different solutions. We discuss the characteristics of the solutions, from the point of view of the singularities of the spacetime, by examining the behavior of the Kretschmann scalar as well as of the geodesics with respect to their completeness. We analyze some aspects of the thermodynamics, particularizing to one of the solutions obtained, namely, for <span>(beta = nicefrac {-1}{2})</span>, in which case the regularity of Bardeen black hole is preserved. We also show that there is an incompatibility between the temperature arising from the first law of the black hole thermodynamics and the one using the surface gravity. Some thermodynamic quantities are obtained and analyzed, as for example, pressure, heat capacity, and the critical points, and we show how these quantities change for different values of the parameter <i>q</i> associated with the original Bardeen solution, as well as with the parameter <i>b</i> associated with the presence of the fluid of strings. The phase transitions are also analyzed by using the equation of state and the Helmholtz free energy.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"56 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141597278","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
4D Einstein–Gauss–Bonnet cosmology with Chameleon mechanism 具有变色龙机制的四维爱因斯坦-高斯-波纳宇宙学
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2024-07-08 DOI: 10.1007/s10714-024-03270-4
Andronikos Paliathanasis
{"title":"4D Einstein–Gauss–Bonnet cosmology with Chameleon mechanism","authors":"Andronikos Paliathanasis","doi":"10.1007/s10714-024-03270-4","DOIUrl":"10.1007/s10714-024-03270-4","url":null,"abstract":"<div><p>We explore the impact of the chameleon mechanism in scalar field Einstein–Gauss–Bonnet gravity on the dynamics of cosmological parameters. Conducting a thorough analysis of the phase space, we identify conditions under which the future attractor does not depict a singular universe. Our conclusion is that although Einstein–Gauss–Bonnet scalar field gravity offers an inflationary solution as a future attractor, it is unable to account for the late-time acceleration of the universe and it can not describe a universe similar to that provide by the <span>(Lambda )</span>CDM model. On the other hand, when the matter source is described by a massless scalar field, then the de Sitter universe is a future attractor. However, the hyperbolic inflationary solution provided by the two scalar fields does not exist.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"56 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141556761","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
The d’Alembert solution in hyperboloidal foliations 双曲面中的达朗贝尔解法
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2024-07-08 DOI: 10.1007/s10714-024-03272-2
Juan A. Valiente Kroon, Lidia J. Gomes Da Silva
{"title":"The d’Alembert solution in hyperboloidal foliations","authors":"Juan A. Valiente Kroon,&nbsp;Lidia J. Gomes Da Silva","doi":"10.1007/s10714-024-03272-2","DOIUrl":"10.1007/s10714-024-03272-2","url":null,"abstract":"<div><p>We explicitly construct the analogue of the d’Alembert solution to the 1+1 wave equation in an hyperboloidal setting. This hyperboloidal d’Alembert solution is used, in turn, to gain intuition into the behaviour of solutions to the wave equation in a hyperboloidal foliation and to explain an apparently anomalous permanent displacement of the solution in numerical simulations discussed in the literature.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"56 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-024-03272-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141557035","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
A dynamical system analysis of bouncing cosmology with spatial curvature 具有空间曲率的弹跳宇宙学的动力系统分析
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2024-07-06 DOI: 10.1007/s10714-024-03265-1
Soumya Chakraborty, Sudip Mishra, Subenoy Chakraborty
{"title":"A dynamical system analysis of bouncing cosmology with spatial curvature","authors":"Soumya Chakraborty,&nbsp;Sudip Mishra,&nbsp;Subenoy Chakraborty","doi":"10.1007/s10714-024-03265-1","DOIUrl":"10.1007/s10714-024-03265-1","url":null,"abstract":"<div><p>The present work deals with a FLRW cosmological model with spatial curvature and minimally coupled scalar field as the matter content. The curvature term behaves as a perfect fluid with the equation of state parameter <span>(omega _{mathcal {K}}=-frac{1}{3})</span>. Using suitable transformation of variables, the evolution equations are reduced to an autonomous system for both power law and exponential form of the scalar potential. The critical points are analyzed with center manifold theory and stability has been discussed. Also, critical points at infinity have been studied using the notion of Poincaré sphere. Finally, the cosmological implications of the critical points and cosmological bouncing scenarios are discussed. It is found that the cosmological bounce takes place near the points at infinity when the non-isolated critical points on the equator of the Poincaré sphere are saddle or saddle-node in nature.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"56 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553446","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
Effeciency of higher dimensional black holes as particle accelerators 高维黑洞作为粒子加速器的效率
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2024-07-05 DOI: 10.1007/s10714-024-03269-x
Fatemeh Behdadkia, Behrouz Mirza, Masoumeh Tavakoli
{"title":"Effeciency of higher dimensional black holes as particle accelerators","authors":"Fatemeh Behdadkia,&nbsp;Behrouz Mirza,&nbsp;Masoumeh Tavakoli","doi":"10.1007/s10714-024-03269-x","DOIUrl":"10.1007/s10714-024-03269-x","url":null,"abstract":"<div><p>The center-of-mass energy of two colliding particles could be arbitrarily high in the vicinity of event horizons of the extremal Myers-Perry black holes if the angular momentum of colliding particles is fine-tuned to the critical values. We investigate the maximum efficiency of two colliding particles in four and six dimensions. The efficiency of collision for two particles near the four-dimensional Kerr black holes is 130%. We show that the efficiency increases to 145% for collision in six dimensions. We also show that the region for the polar angle in which the particle can reach the high energy is larger when the dimension of space-time increases.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"56 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-024-03269-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553442","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
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