General Relativity and Gravitation最新文献

{"title":"A numerical framework for studying asymptotic quantities","authors":"Breanna Camden,&nbsp;Jörg Frauendiener,&nbsp;Joseph Galinski,&nbsp;Kaushal Pillay,&nbsp;Chris Stevens,&nbsp;Sebenele Thwala","doi":"10.1007/s10714-025-03399-w","DOIUrl":"10.1007/s10714-025-03399-w","url":null,"abstract":"<div><p>In this contribution we present an overview of our work on the numerical simulation of the perturbation of a black hole space-time by incoming gravitational waves. The formulation we use is based on Friedrich’s general conformal equations which have the unique property that they allow access to the asymptotic region of an asymptotically regular space-time. In our approach we set up an initial boundary value problem on a finite boundary, which cleanly separates the initial conditions, a static black hole, from the perturbation, an incoming gravitational wave specified by a spin-2 function on the time-like boundary. The main advantage of this approach is that the finite boundary expands fast enough to reach null-infinity where the asymptotic properties can be studied. This provides, for the first time, a direct relationship between finite initial and boundary data and asymptotic quantities within one simulation. We discuss the possibilities and limitations of this approach.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 4","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03399-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143778006","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":"Gyroscopic precession in Reissner–Nordström spacetime","authors":"Paulami Majumder,&nbsp;K. Rajesh Nayak","doi":"10.1007/s10714-025-03395-0","DOIUrl":"10.1007/s10714-025-03395-0","url":null,"abstract":"<div><p>In this work, we investigate a static spherically symmetric Reissner–Nordström event horizon and a naked singularity by analyzing the behavior of a gyroscope transported along a timelike curve. We find that the precession frequency remains finite for both the black hole and the naked singularity as long as the trajectory is timelike. Our objective is to quantify the differences in the gyroscope’s precession behavior when approaching an event horizon versus a naked singularity. Additionally, we explore the potential for distinguishing between an event horizon and a naked singularity by examining the reversal of the precession frequency.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 4","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143740627","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":"A healthier stochastic semiclassical gravity: world without Schrödinger cats","authors":"Lajos Diósi","doi":"10.1007/s10714-025-03396-z","DOIUrl":"10.1007/s10714-025-03396-z","url":null,"abstract":"<div><p>Semiclassical gravity couples classical gravity to the quantized matter in meanfield approximation. The meanfield coupling is problematic for two reasons. First, it ignores the quantum fluctuation of matter distribution. Second, it violates the linearity of the quantum dynamics. The first problem can be be mitigated by allowing stochastic fluctuations of the geometry but the second problem lies deep in quantum foundations. Restoration of quantum linearity requires a conceptual approach to hybrid classical-quantum coupling. Studies of the measurement problem and the quantum-classical transition point the way to a solution. It is based on a postulated mechanism of spontaneous quantum monitoring plus feedback. This approach eliminates Schrödinger cat states, takes quantum fluctuations into the account, and restores the linearity of quantum dynamics. Such conceptionally ’healthier’ semiclassical theory is captivating, exists in the Newtonian limit, but its relativistic covariance hits a wall. Here we will briefly recapitulate the concept and its realization in the nonrelativistic limit. We emphasize that the long-known obstacles to the relativistic extension lie in quantum foundations.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 4","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03396-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143740628","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":"Cooling and heating regions of Joule-Thomson expansion for AdS black holes: Einstein-Maxwell-power-Yang-Mills and Kerr Sen black holes","authors":"Mohammad Reza Alipour,&nbsp;Saeed Noori Gashti,&nbsp;Mohammad Ali S. Afshar,&nbsp;Jafar Sadeghi","doi":"10.1007/s10714-025-03393-2","DOIUrl":"10.1007/s10714-025-03393-2","url":null,"abstract":"<div><p>In this paper, we study the Joule-Thomson Expansion process for two types of black holes: AdS-Einstein-Maxwell-power-Yang-Mills (AEMPYM) and AdS-Kerr-Sen (AKS). Our study focuses on understanding how various parameters influence the Joule-Thomson Coefficient, the inversion curve, and the ratio of minimum inversion temperature to critical temperature. For the AKS black hole, we observe that the isenthalpic curves can exhibit either cooling or heating behavior. This behavior is determined by the inversion curve, which is affected by the black hole’s mass and specific parameters such as <i>b</i> (parameter signifies the ionic charge of the black hole) and <i>a</i> (rotation parameter). In the case of the AEMPYM black hole, our findings reveal that the ratio of minimum inversion temperature to critical temperature approaches a specific value as Maxwell’s charge increases. This ratio remains constant for certain parameter values, while it varies for others. Specifically, when the parameter <span>(q)</span> (real positive parameter of AEMPYM black hole) is greater than 1, the ratio is almost equal to 1/2 as Maxwell’s charge <span>(C)</span> increases. When q equals 1/2, the ratio is exactly 1/2 for all values of <span>(C)</span>. For values of <span>(q)</span> between 1/2 and 1, the ratio is close to 1/2, and for values of <span>(q)</span> between 0 and 1/2, the ratio decreases, moving away from 1/2. For the AKS black hole, we find that specific parameter values, such as <span>(a = 0.00951)</span> and <span>(b = 0.00475)</span>, yield a ratio of minimum inversion temperature to a critical temperature that is approximately 1/2. This consistency across different parameter values highlights the robustness of our findings. Finally, we compare our results with those reported in the existing literature, providing a comprehensive summary in detailed tables. This comparison not only validates our findings but also situates them within the broader context of black hole thermodynamics and the Joule-Thomson effect.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 3","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03393-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143707175","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 stability problem for extremal black holes","authors":"Mihalis Dafermos","doi":"10.1007/s10714-025-03394-1","DOIUrl":"10.1007/s10714-025-03394-1","url":null,"abstract":"<div><p>I present a series of conjectures aiming to describe the general dynamics of the Einstein equations of classical general relativity in the vicinity of extremal black holes. I will reflect upon how these conjectures transcend older paradigms concerning extremality and near-extremality, in particular, the so-called “third law of black hole thermodynamics”, which viewed extremality as an unattainable limit, and the “overspinning/overcharging” scenarios, which viewed extremality as a harbinger of naked singularities. Finally, I will outline some of the difficulties in proving these conjectures and speculate on what it could mean if the conjectures turn out not to be true.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 3","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03394-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143645488","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":"Some thoughts about black holes in asymptotic safety","authors":"Alessia Platania","doi":"10.1007/s10714-025-03390-5","DOIUrl":"10.1007/s10714-025-03390-5","url":null,"abstract":"<div><p>We discuss the current status of black holes within quantum gravity approaches based on quantum field theory, and particularly asymptotic safety. We highlight key open questions in the field, including the difficulty of deriving global solutions from the effective action, the role of matter in constraining the set of all possible alternatives to classical black holes, the importance of the formation probability, and its implications for both conceptual and practical aspects. These challenges highlight some necessary developments in the field and single out a few future directions, which could be promising to progress our understanding of black holes in quantum gravity.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 3","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622000","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":"On black holes in teleparallel torsion theories of gravity","authors":"A. A. Coley,&nbsp;N. T. Layden,&nbsp;D. F. López","doi":"10.1007/s10714-025-03387-0","DOIUrl":"10.1007/s10714-025-03387-0","url":null,"abstract":"<div><p>We first present an overview of the Schwarzschild vacuum spacetime within general relativity, with particular emphasis on the role of scalar polynomial invariants and the null frame approach (and the related Cartan invariants), that justifies the conventional interpretation of the Schwarzschild geometry as a black hole spacetime admitting a horizon (at <span>(r=2M)</span> in Schwarzschild coordinates) shielding a singular point at the origin. We then consider static spherical symmetric vacuum teleparallel spacetimes in which the torsion characterizes the geometry, and the scalar invariants of interest are those constructed from the torsion and its (covariant) derivatives. We investigate the Schwarzschild-like spacetime in the teleparallel equivalent of general relativity and find that the torsion scalar invariants (and, in particular, the scalar <i>T</i>) diverge at the putative “Schwarzschild” horizon. In this sense the resulting spacetime is <i>not</i> a black hole spacetime. We then briefly consider the Kerr-like solution in the teleparallel equivalent of general relativity and obtain a similar result. Finally, we investigate static spherically symmetric vacuum spacetimes within the more general <i>F</i>(<i>T</i>) teleparallel gravity and show that if a such a geometry admits a horizon, then the torsion scalar <i>T</i> necessarily diverges there; consequently in this sense such a geometry also does <i>not</i> represent a black hole.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 3","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143627741","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 collapse of Bose–Einstein condensate dark matter in generalized Vaidya spacetime","authors":"Prabir Rudra","doi":"10.1007/s10714-025-03392-3","DOIUrl":"10.1007/s10714-025-03392-3","url":null,"abstract":"<div><p>In this work we study the gravitational collapse procedure in generalized Vaidya spacetime with Bose–Einstein condensate dark matter density profile. We use the generalized Vaidya metric to simulate the spacetime of a big star and subsequently obtain the field equations. Then we proceed to determine the star system’s mass parameter by solving the field equations. Then the gravitational collapse mechanism is investigated using the derived solutions. Investigating the nature of the singularity (if formed) as the end state of the collapse is the main goal. Dark matter in the form of Bose–Einstein condensate is expected to play a crucial role in the fate of the collapse. We see that there is a possibility of the formation of both black holes and naked singularities as the end state of the collapse depending upon the initial conditions. The junction conditions are derived with a Vaidya exterior and a Friedmann interior and some important insights are obtained. A Penrose diagram showing the causal relations between the spacetimes is generated and studied in detail.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 3","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621989","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":"Energy estimates for the good-bad-ugly model","authors":"Miguel Duarte","doi":"10.1007/s10714-025-03389-y","DOIUrl":"10.1007/s10714-025-03389-y","url":null,"abstract":"<div><p>We establish a relationship between the equations that constitute the so-called <i>good-bad-ugly model</i>, whose nonlinearities are known to mimic those present in the Einstein field equations in generalized harmonic gauge. This relationship between ugly fields and good and bad ones stems from the fact that one can write the equation for the rescaled derivative of an ugly along an incoming null direction as a good or a bad equation depending on whether there are source terms or not. This provides a new interpretation of the logarithms of the radial coordinate that show up in expansions of solutions to ugly equations near null infinity. This furthermore allows us to use the Klainerman-Sobolev inequality for the standard wave equation on Cauchy slices to show uniform boundedness for the ugly equation. In the second part of this paper we perform a first order reduction of the ugly equation with given sources in flat space and we radially compactify the coordinates in order to show an energy estimate for that equation on hyperboloidal slices. This result is an important first step towards establishing energy estimates for the hyperboloidal initial value problem of the first order compactified Einstein field equations in generalized harmonic gauge.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 3","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143583462","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":"Classical general relativity effects by magnetars with massive quadrupole, angular momentum and a magnetic dipole","authors":"Alexander Mora-Chaverri,&nbsp;Edwin Santiago-Leandro,&nbsp;Francisco Frutos-Alfaro","doi":"10.1007/s10714-025-03388-z","DOIUrl":"10.1007/s10714-025-03388-z","url":null,"abstract":"<div><p>In this contribution, we obtain classical tests of general relativity using the Hartle-Thorne metric endowed with magnetic dipole and electric charge. This metric represents the approximate stationary spacetime of a massive object with the other characteristics mentioned. These tests are light deflection, time delay, periastron precession, and gravitational redshift. We also provide numerical estimates for real magnetars and magnetar candidates from the McGill magnetar catalog, the millisecond pulsar PSR B1257+12 and for the Sun in low-activity cycles. Our results find that, although the magnetic dipole moment contribution tends to be negligible compared to the total amount, its comparison to the massive quadrupole moment and rotational contributions varies from one classical test to the next. For light deflection, the magnetic dipole contribution is about 2 orders of magnitude smaller, compared to the rotational contribution. The magnetic dipole moment contribution is present, but is about 6 orders of magnitude smaller than the second-order rotational contribution to the periastron precession, 5 orders of magnitude smaller for the time delay, and negligible within the approximation presented for the gravitational redshift. The magnetic dipole contribution for the calculations made with PSR B1257+12 was also negligible, but the rotational and quadrupole moment contributions were more significant, which makes the argument for possible future detection stronger than the magnetar case. The rotation, massive quadrupole moment and magnetic dipole contributions for the Sun turned out to be negligible as well.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 3","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143583461","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}