arXiv - PHYS - General Relativity and Quantum Cosmology最新文献

{"title":"Energy extraction from a rotating black hole via magnetic reconnection: the plunging bulk plasma and orientation angle","authors":"Ye Shen, Ho-Yun YuChih, Bin Chen","doi":"arxiv-2409.07345","DOIUrl":"https://doi.org/arxiv-2409.07345","url":null,"abstract":"Magnetic reconection provides a new avenue to extract energy from a rotating\u0000black hole in astrophysical scenarios. There have been many works studying the\u0000feasibility of extracting energy via magnetic reconnection in the scheme of\u0000magnetohydrodynamics. However, most of them focused on circularly flowing bulk\u0000plasma only, and the influence of orientation angle, the angle between flowing\u0000direction of bulk plasma and ejection direction of plasmoids, was never\u0000carefully considered. In this work, we would like to study the energy\u0000extraction via magnetic reconnection in the plunging plasma, and more\u0000importantly, we analyze the influence of orientation angle in depth. Actually,\u0000we consider the magnetic reconnection occurring in bulk plasma with two kinds\u0000of streamlines, one being the circular flow and the other being the plunging\u0000flow from the ISCO. We find that the plunging plasma has higher\u0000energy-extraction efficiency. Moreover, we notice that it is favorable for\u0000energy extraction when the orientation angle is suitably increased if the bulk\u0000plasma plunges. We further define a quantity to characterize the energy\u0000extraction probability, through which we conclude that the plunging bulk plasma\u0000is much more capable in energy extraction than the circularly flowing one.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Graviscalar quasinormal modes and asymptotic tails of a thick brane","authors":"Qin Tan, Sheng Long, Sheng Long, Jiliang Jing","doi":"arxiv-2409.06947","DOIUrl":"https://doi.org/arxiv-2409.06947","url":null,"abstract":"In this work, we investigate the graviscalar quasinormal modes (QNMs) and\u0000their asymptotic tail behavior of a thick brane. Considering the scalar\u0000perturbations of the thick brane metric, we obtain the main equations of scalar\u0000Kaluza-Klein modes. Based on these equations, the frequencies of the scalar\u0000QNMs of the thick brane are obtained by the Wentzel-Kramers-Brillouin,\u0000asymptotic iteration, and numerical evolution methods. The results show that\u0000the scalar fluctuation of the thick brane has a series of discrete QNMs,\u0000similar to the tensor perturbation of the brane. These modes appear as decaying\u0000massive scalar particles in four-dimensional spacetime. We also studied in\u0000detail the late time tails of these QNMs and found that some modes have slowly\u0000decaying oscillatory tails that may be new sources of the gravitational wave\u0000backgrounds. Obviously, the QNMs contain the information of the brane and are\u0000characteristic modes of the thick brane.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"50 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gravitational wave polarisations in nonminimally coupled gravity","authors":"Miguel Barroso Varela, Orfeu Bertolami","doi":"arxiv-2409.07625","DOIUrl":"https://doi.org/arxiv-2409.07625","url":null,"abstract":"The properties of metric perturbations are determined in the context of an\u0000expanding Universe governed by a modified theory of gravity with a non-minimal\u0000coupling between curvature and matter. We analyse the dynamics of the 6\u0000components of a general helicity decomposition of the metric and stress-energy\u0000perturbations, consisting of scalar, vector and tensor sectors. The tensor\u0000polarisations are shown to still propagate luminally, in agreement with recent\u0000data from gravitational interferometry experiments, while their magnitude\u0000decays with an additional factor sourced by the nonminimal coupling. We show\u0000that the production of these modes is associated with a modified quadrupole\u0000formula at leading order. The vector perturbations still exhibit no radiative\u0000behaviour, although their temporal evolution is found to be modified, with\u0000spatial dependence remaining unaffected. We establish that the scalar\u0000perturbations can no longer be treated as identical. We investigate the scalar\u0000sector by writing the modified model as an equivalent two-field scalar-tensor\u0000theory and find the same scalar degrees of freedom as in previous literature.\u0000The different sectors are paired with the corresponding polarisation modes,\u0000which can be observationally measured by their effects on the relative motion\u0000of test particles, thus providing the possibility of testing the modified\u0000theory and constraining its parameters.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dark Energy: A Dynamical Systems Approach to the Reconstruction of the Equation of State","authors":"Bob Osano","doi":"arxiv-2409.07053","DOIUrl":"https://doi.org/arxiv-2409.07053","url":null,"abstract":"This correspondence delves into the application of dynamical systems\u0000methodologies within the context of cosmology, specifically addressing a\u0000preliminary strategy for determining the range for the equation of state for\u0000dark energy ($omega_{DE}$). Our findings suggest that the preferred range for\u0000$omega_{DE}$ is between -1.1 and -0.6.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rotating black holes in de Rham-Gabadadze-Tolley massive gravity","authors":"Ping Li, Jiang-he Yang","doi":"arxiv-2409.07169","DOIUrl":"https://doi.org/arxiv-2409.07169","url":null,"abstract":"We delve into the rotating black hole solutions in de Rham-Gabadadze-Tolley\u0000(dRGT) massive gravity. Employing an analytical approach, we solve the field\u0000equations for scenarios both devoid of matter and in the presence of an\u0000electromagnetic field. Consequently, we obtain black hole solutions that extend\u0000beyond the Kerr-Newman family. These solutions are characterized not only by\u0000mass $M$, electric charge $Q$, and angular momentum $a$, but also by the\u0000graviton mass term, which introduces the cosmological constant $Lambda$ and\u0000the St\"uckelberg charge $S$ into the black hole parameters. Instead of the\u0000St\"uckelberg field $phi^a$, we utilize the matrix $gamma^2$ to seek\u0000solutions. To derive the St\"uckelberg field $phi^a$ from a given matrix\u0000$gamma^2$ for axisymmetric metrics, one must relax the constraint on the\u0000reference metric $f_{ab} = eta_{ab}$. These solutions potentially serve as\u0000candidates for astrophysical black holes.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Overcharging a nonsingular black hole in general relativity: the nonlinear electrodynamic field effects","authors":"Wei-Jie Miao, Si-Jiang Yang","doi":"arxiv-2409.07305","DOIUrl":"https://doi.org/arxiv-2409.07305","url":null,"abstract":"Recent research has showed that, by accounting for the nonlinear\u0000electrodynamic field effects on the motion of test charged particles, it is\u0000possible to destroy an extremal and near-extremal black hole [Phys.Rev.D 101\u0000(2020) 12, 124067]. Inspired by this perspective, we explore the potential for\u0000the destruction of a nonsingular black hole within the framework of general\u0000relativity, where gravity couples with nonlinear electrodynamic field. By\u0000combining the theory of nonlinear electrodynamics in curved spacetime, we\u0000obtain the conserved charges for test charged particles, then investigate the\u0000possibility of destroying the event horizon of the Ay'on--Beato Garc'i a\u0000(ABG) nonsingular black hole by test charged particle and complex scalar field.\u0000We obtain the intervals for the parameter of the particle and scalar field\u0000which allow us to destroy the event horizon of an extremal and near-extremal\u0000ABG black hole black hole. Due to the nonlinear electrodynamic field effects,\u0000both an extremal and near-extremal black hole can be destroyed. Interestingly,\u0000we find that the parameter intervals for the test charged particle and the test\u0000complex scalar field that can destroy the event horizon of an extremal black\u0000hole are identical. Importantly, as the ABG black hole is a nonsingular black\u0000hole, our findings remain consistent with the weak cosmic censorship conjecture\u0000and might provide a viable approach to observe the internal structure of a\u0000black hole.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"128 2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Which is which? Identification of the two compact objects in gravitational-wave binaries","authors":"Davide Gerosa, Viola De Renzis, Federica Tettoni, Matthew Mould, Alberto Vecchio, Costantino Pacilio","doi":"arxiv-2409.07519","DOIUrl":"https://doi.org/arxiv-2409.07519","url":null,"abstract":"Compact objects observed in gravitational-wave astronomy so far always come\u0000in pairs and never individually. Identifying the two components of a binary\u0000system is a delicate operation that is often taken for granted. The labeling\u0000procedure (i.e. which is object \"1\" and which is object \"2\") effectively acts\u0000as systematics, or equivalently an unspecified prior, in gravitational-wave\u0000data inference. The common approach is to label the objects solely by their\u0000masses, on a sample-by-sample basis; while intuitive, this leads to\u0000degeneracies when binaries have comparable masses. Instead, we argue that\u0000object identification should be tackled using the posterior distribution as a\u0000whole. We frame the problem in terms of constrained clustering -- a flavor of\u0000semi-supervised machine learning -- and find that unfolding the labeling\u0000systematics can significantly impact, and arguably improve, our interpretation\u0000of the data. In particular, the precision of black-hole spin measurements\u0000improves by up to 50%, spurious multimodalities and tails tend to disappear,\u0000posteriors become closer to Gaussian distributions, and the identification of\u0000the nature of the object (i.e. black hole vs. neutron star) is facilitated. We\u0000estimate that about 10% of the LIGO/Virgo posterior samples are affected by\u0000this relabeling, i.e. they might have been attributed to the wrong compact\u0000object in the observed binaries.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the Weyl Tensor for a Curved Spacetime Endowed with a Torsionful Affinity","authors":"J. G. Cardoso","doi":"arxiv-2409.07364","DOIUrl":"https://doi.org/arxiv-2409.07364","url":null,"abstract":"We transcribe into the framework of the {epsilon}-formalism of Infeld and\u0000van der Waerden the world definition of the Weyl tensor for a curved spacetime\u0000that occurs in the realm of Einstein-Cartan's theory. The resulting expression\u0000shows us that it is not possible to attain any general condition for conformal\u0000flatness in such a spacetime even if wave functions for gravitons are\u0000eventually taken to vanish identically. A short discussion on the situation\u0000concerning the limiting case of general relativity is presented thereafter.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"136 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conversion of high frequency relic gravitational waves into photons in cosmological magnetic field","authors":"L. A. Panasenko, A. O. Chetverikov","doi":"arxiv-2409.07063","DOIUrl":"https://doi.org/arxiv-2409.07063","url":null,"abstract":"This work continues the research presented in the article [1], where we\u0000estimate the Gertsenshtein effect's influence on the long-wavelength part of\u0000relic gravitational wave spectrum. Here, the differential equation system for\u0000the Gertsenshtein effect in Friedman-LeMaitre-Robertson-Walker universe,\u0000derived in [1], is simplified for gravitational waves in the under-horizon\u0000regime during radiation dominance epoch. Then, the obtained system is solved\u0000analytically. As a result of the solution analysis a conclusion was made about\u0000a significant increase of relic GWs with the frequencies $ kgtrsim 10^{-11}$\u0000Hz for magnetic field strength about 1 nGs. In addition, at the end of the\u0000article model dependency of the result is discussed","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"What is the nature of GW230529? An exploration of the gravitational lensing hypothesis","authors":"Justin Janquart, David Keitel, Rico K. L. Lo, Juno C. L. Chan, Jose Marìa Ezquiaga, Otto A. Hannuksela, Alvin K. Y. Li, Anupreeta More, Hemantakumar Phurailatpam, Neha Singh, Laura E. Uronen, Mick Wright, Naresh Adhikari, Sylvia Biscoveanu, Tomasz Bulik, Amanda M. Farah, Anna Heffernan, Prathamesh Joshi, Vincent Juste, Atul Kedia, Shania A. Nichols, Geraint Pratten, C. Rawcliffe, Soumen Roy, Elise M. Sänger, Hui Tong, M. Trevor, Luka Vujeva, Michael Zevin","doi":"arxiv-2409.07298","DOIUrl":"https://doi.org/arxiv-2409.07298","url":null,"abstract":"On the 29th of May 2023, the LIGO-Virgo-KAGRA Collaboration observed a\u0000compact binary coalescence event consistent with a neutron star-black hole\u0000merger, though the heavier object of mass 2.5-4.5 $M_odot$ would fall into the\u0000purported lower mass gap. An alternative explanation for apparent observations\u0000of events in this mass range has been suggested as strongly gravitationally\u0000lensed binary neutron stars. In this scenario, magnification would lead to the\u0000source appearing closer and heavier than it really is. Here, we investigate the\u0000chances and possible consequences for the GW230529 event to be gravitationally\u0000lensed. We find this would require high magnifications and we obtain low rates\u0000for observing such an event, with a relative fraction of lensed versus unlensed\u0000observed events of $2 times 10^{-3}$ at most. When comparing the lensed and\u0000unlensed hypotheses accounting for the latest rates and population model, we\u0000find a 1/58 chance of lensing, disfavoring this option. Moreover, when the\u0000magnification is assumed to be strong enough to bring the mass of the heavier\u0000binary component below the standard limits on neutron star masses, we find high\u0000probability for the lighter object to have a sub-solar mass, making the binary\u0000even more exotic than a mass-gap neutron star-black hole system. Even when the\u0000secondary is not sub-solar, its tidal deformability would likely be measurable,\u0000which is not the case for GW230529. Finally, we do not find evidence for extra\u0000lensing signatures such as the arrival of additional lensed images, type-II\u0000image dephasing, or microlensing. Therefore, we conclude it is unlikely for\u0000GW230529 to be a strongly gravitationally lensed binary neutron star signal.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}