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Static Einstein–Maxwell spacetime invariant by translation Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20211018
Leandro, Benedito, de Melo, Ana Paula, Menezes, Ilton, Pina, RomildoIn this paper we study the static Einstein–Maxwell space when it is conformal to an ndimensional pseudoEuclidean space, which is invariant under the action of an \((n1)\)dimensional translation group. We also provide a complete classification of such space.

Scalar quasinormal modes for $$2+1$$ 2 + 1 dimensional Coulomblike AdS black holes from nonlinear electrodynamics Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20211016
Aragón, Almendra, González, P. A., Saavedra, Joel, Vásquez, YerkoWe study the propagation of scalar fields in the background of \(2+1\)dimensional Coulomblike AdS black holes, and we show that such propagation is stable under Dirichlet boundary conditions. Then, we solve the Klein–Gordon equation by using the pseudospectral Chebyshev method and the Horowitz–Hubeny method, and we find the quasinormal frequencies. Mainly, we find that the quasinormal frequencies

Nonstaticity with type II, III, or IV matter field in $$f(R_{\mu \nu \rho \sigma },g^{\mu \nu })$$ f ( R μ ν ρ σ , g μ ν ) gravity Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20211014
Maeda, HidekiIn all \(n(\ge 3)\)dimensional gravitation theories whose Lagrangians are functions of the Riemann tensor and metric, we show that static solutions are absent unless the total energymomentum tensor for matter fields is of type I in the Hawking–Ellis classification. In other words, there is no hypersurfaceorthogonal timelike Killing vector in a spacetime region with an energymomentum tensor of type

Repulsive gravity effects in horizon formation Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210927
Pugliese, Daniela, Quevedo, HernandoRepulsive gravity is a well known characteristic of naked singularities. In this work, we explore light surfaces and find new effects of repulsive gravity. We compare Kerr naked singularities with the corresponding black hole counterparts and find certain structures that are identified as horizon remnants. We argue that these features might be significant for the comprehension of processes that lead

Lifshitz scaling effects on the holographic paramagneticferromagnetic phase transition Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210925
Ghotbabadi, B. Binaei, Sheykhi, A., Bordbar, G. H.We disclose the effects of Lifshitz dynamical exponent z on the properties of holographic paramagneticferromagnetic phase transition in the background of Lifshitz spacetime. To preserve the conformal invariance in higher dimensions, we consider the PowerMaxwell (PM) electrodynamics as our gauge field. We introduce a massive 2form coupled to the PM field and perform the numerical shooting method

Correspondence between quasinormal modes and the shadow radius in a wormhole spacetime Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210916
Jusufi, KimetIn this paper we study the correspondence between the real part of quasinormal modes and the shadow radius in a wormhole spacetime. Firstly we consider the above correspondence in a static and spherically symmetric wormhole spacetime and then explore this correspondence numerically by considering different wormhole models having specific redshift functions. To this end, we generalize this correspondence

Thermodynamical critical properties of 4D charged AdS massive black hole by thermoshadow method Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210913
Liu, Yun, Nie, Zhenxiong, Chen, Juhua, Wang, YongjiuIn this paper, we investigate the effect of the characteristic parameter m of the black hole solution in massive gravity on the thermodynamical critical properties of the black hole. We find that when the characteristic parameter m is less than the critical value \(m_{c}\), there is no the phase transition in the black hole system. On this basis, we use the black hole shadow radius to detect the phase

VaidyaBonnor black hole in monopolede Sitter space with variable $$\varLambda (u)$$ Λ ( u ) Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210903
Vaiphei, ST Khaiminthang, Ibohal, Ng., Singh, M. R.In this paper, we propose a class of embedded solutions of Einstein’s field equations with the de Sitter cosmological function \(\varLambda (u)\). This class of solutions describes VaidyaBonnormonopolede Sitter spacetime with variable \(\varLambda (u)\). It may also be interpreted as VaidyaBonnor black hole in monopolede Sitter space with variable \(\varLambda (u)\). It is shown the natural modification

Numerical evolution of the interior geometry of charged black holes Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210902
Chesler, Paul M.Previously, we developed a late time approximation scheme to study the interior geometry of black holes. In the present paper we test this scheme with numerical relativity simulations. In particular, we present numerical relativity simulations of the interior geometry of charged spherically symmetric twosided black holes with a spacelike singularity at \(r = 0\). Our numerics are in excellent agreement

Modeling the motion of a bright spot in jets from black holes M87* and SgrA* Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210830
Dokuchaev, Vyacheslav I., Nazarova, Natalia O.We study the general relativistic motion of a bright spot in a jet from an accreting black hole. The corresponding lensed images of the moving bright spot are calculated numerically in discrete time intervals along the bright spot trajectory in the Kerr spacetime framework. As representative examples, we consider the cases of supermassive black holes SgrA* and M87*. Astrophysical observations of the

Polytropic antide Sitter black hole Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210821
Salti, M., Aydogdu, O., Sogut, K.In the present study, we mainly discuss the features of polytropic antide Sitter (PAdS) black hole solution, which can be taken into account also as a stable configuration for dark energy stars. A dark energy star is a hypothetical compact astrophysical object and it has gained astrophysical relevance in literature for several reasons, for instance, it may be another interpretation for observations

Consistency between dynamical and thermodynamical stabilities for charged selfgravitating perfect fluid Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210820
Yang, Wei, Fang, Xiongjun, Jing, JiliangThe entropy principle shows that, for selfgravitating perfect fluid, the Einstein field equations can be derived from the extrema of the total entropy, and the thermodynamical stability criterion are equivalent to the dynamical stability criterion. In this paper, we recast the dynamical criterion for the charged selfgravitating perfect fluid in Einstein–Maxwell theory, and further give the criterion

Solar system, astrophysics, and cosmology from the derivative expansion Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210817
Haddad, Nidal, Haddad, FateenIn this paper we show how the solar system, the galactic, and the cosmological scales, are accommodated in a single framework, namely, in the derivative expansion framework. We construct a locally inertial static metric, based on the Einstein equations and on the derivative expansion method, which describes a Schwarzschild black hole immersed in dark matter and dark energy. The leading order metric

Black hole in NielsenOlesen vortex Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210816
Ghosh, Kumar J. B.In this article, we calculate the classical vortex solution of a spontaneously broken gauge theory interacting with gravity in (2+1)dimension. We also calculate the conditions for the formation of a (2+1)dimensional black hole due to magnetic vortex (a NielsenOlesen vortex). The semiclassical Hawking temperature for this black hole is calculated, where we see that the temperature of a BTZ black

Morris–Thorne wormholes in modified f(R, T) gravity Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210811
Chanda, A., Dey, S., Paul, B. C.Wormhole solutions obtained by Morris and Thorne (MT) in general relativity (GR) is investigated in a modified theory of gravity. In the gravitational action, we consider f(R, T) which is a function of the Ricci scalar (R) and the trace of the energymomentum tensor (T). In the framework of a modified gravity described by \(f(R,T)=R+\alpha R^{2}+\lambda T^{\beta }\), where \(\alpha \), \(\beta \) and

Modifications to the signal from a gravitational wave event due to a surrounding shell of matter Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210806
Naidoo, Monos, Bishop, Nigel T., van der Walt, Petrus J.In previous work, we established theoretical results concerning the effect of matter shells surrounding a gravitational wave (GW) source, and we now apply these results to astrophysical scenarios. Firstly, it is shown that GW echoes that are claimed to be present in LIGO data of certain events, could not have been caused by a matter shell. However, it is also shown that there are scenarios in which

Stability analysis of geodesics and quasinormal modes of a dual stringy black hole via Lyapunov exponents Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210805
Giri, Shobhit, Nandan, HemwatiWe investigate the stability of both timelike as well as null circular geodesics in the vicinity of a dual (3+1) dimensional stringy black hole (BH) spacetime by using an excellent tool socalled Lyapunov exponent. The proper time (\(\tau \)) Lyapunov exponent (\(\lambda _{p}\)) and coordinate time (t) Lyapunov exponent (\(\lambda _{c}\)) are explicitly derived to analyze the stability of equatorial

Inflation with Gauss–Bonnet and Chern–Simons highercurvaturecorrections in the view of GW170817 Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210804
Venikoudis, S. A., Fronimos, F. P.Inflationary era of our Universe can be characterized as semiclassical because it can be described in the context of fourdimensional Einstein’s gravity involving quantum corrections. These string motivated corrections originate from quantum theories of gravity such as superstring theories and include higher gravitational terms as, Gauss–Bonnet and Chern–Simons terms. In this paper we investigated

Particle motion in a spacetime of a 3D Einstein gravity with torsion Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210729
Kaya, R., Özçelik, H. T.We analyze the motion of both massive and massless particles in a model with spacetime of 3D Einstein gravity with torsion. We consider the spinor field and the massless scalar field as the source of torsion respectively. Following the Hamilton–Jacobi formalism, we investigate the effective potential of radial motion for test particles in a homogeneous and isotropic spacetime with torsion. We show

Geometry of Vaidya spacetimes Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210724
Armand Coudray, JeanPhilippe NicolasWe investigate the geometrical structure of Vaidya’s spacetime in the case of a white hole with decreasing mass, stabilising to a black hole in finite or infinite time or evaporating completely. Our approach relies on a detailed analysis of the ordinary differential equation describing the incoming principal null geodesics, among which are the generators of the past horizon. We devote special attention

Thermodynamics of a static electricmagnetic black hole in EinsteinBornInfeldAdS theory with different horizon geometries Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210723
M. B. Tataryn, M. M. StetskoWe consider black hole solutions with electric and magnetic sources in the fourdimensional EinsteinBornInfeldAdS theory with spherical, planar and hyperbolic horizon geometries. Exact analytical solutions for the metric function, electric and magnetic fields were obtained and they recover the RNAdS black hole in the limit \(\beta \rightarrow +\infty \) for spherical horizon in the absence of the

Geometrothermodynamics of black holes with a nonlinear source Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210722
Alberto SánchezWe study thermodynamics and geometrothermodynamics of a particular black hole configuration with a nonlinear source. We use the mass as fundamental equation, from which it follows that the curvature radius must be considered as a thermodynamic variable, leading to an extended equilibrium space. Using the formalism of geometrothermodynamics, we show that the geometric properties of the thermodynamic

The effect of stationary axisymmetric spacetimes in interferometric visibility Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210721
Marcos L. W. Basso, Jonas MazieroIn this article, we consider a scenario in which a spin1/2 quanton goes through a superposition of corotating and counterrotating circular paths, which play the role of the paths of a Mach–Zehnder interferometer in a stationary and axisymmetric spacetime. Since the spin of the particle plays the role of a quantum clock, as the quanton moves in a superposed path it gets entangled with the momentum

Energy formula for NewmanUntiTamburino class of black holes Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210717
Parthapratim PradhanWe compute the surface energy (\(\mathcal{E}_{s}^{\pm }\)), the rotational energy (\(\mathcal{E}_{r}^{\pm }\)) and the electromagnetic energy (\(\mathcal{E}_{em}^{\pm }\)) for NewmanUntiTamburino (NUT) class of black hole having the event horizon (\(\mathcal{H}^{+}\)) and the Cauchy horizon (\(\mathcal{H}^{}\)). Remarkably, we find that the mass parameter can be expressed as sum of three energies

Nonlocal imprints of gravity on quantum theory Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210716
Michael Maziashvili, Zurab K. SilagadzeDuring the last two decades or so much effort has been devoted to the discussion of quantum mechanics (QM) that in some way incorporates the notion of a minimum length. This upsurge of research has been prompted by the modified uncertainty relation brought about in the framework of string theory. In general, the implementation of minimum length in QM can be done either by modification of position and

Cosmological implications of the hydrodynamical phase of group field theory Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210701
Luciano Gabbanelli, Silvia De BianchiIn this review we focus on the main cosmological implications of the Group Field Theory approach, according to which an effective continuum macroscopic dynamics can be extracted from the underlying formalism for quantum gravity. Within this picture what counts is the collective behaviour of a large number of quanta of geometry. The resulting state is a condensatelike structure made of “pregeometric”

Generalized Dirac Equation for a particle in a gravitational field Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210701
Daniel Chemisana, Jaume Giné, Jaime MadridThe existence of a minimal observable length modifies the Heisenberg’s uncertainty principle at Plank scales and leads to some modifications of the Dirac equation. Here, we consider the generalized uncertainty principle (GUP) theory in order to deduce a generalized Dirac equation and solve its eigenvalue problem for a particle within a gravitational field created by a central mass. We use two different

Propagation of gravitational waves in various cosmological backgrounds Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210630
Sushovan Mondal, Saif Ali, Shanima Shahul, Narayan Banerjee, Golam Mortuza HossainThe present work investigates some exact solutions of the gravitational wave equation in some widely used cosmological spacetimes. The examples are taken from spatially flat and closed isotropic models as well as Kasner metric which is anisotropic. Various matter distributions are considered, from the standard dust or radiation distribution to exotic matters like that with an equation of state \(P

Phase space analysis of Tsallis agegraphic dark energy Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210629
Hai Huang, Qihong Huang, Ruanjing ZhangBased on the generalized Tsallis entropy and holographic hypothesis, the Tsallis agegraphic dark energy (TADE) was proposed by introducing the timescale as infrared cutoff. In this paper, we analyze the evolution of the universe in the TADE model and the new Tsallis agegraphic dark energy (NTADE) model by considering an interaction between dark matter and dark energy as \(Q=H(\alpha \rho _{m}+\beta

Particle creation in some LRS Bianchi I models Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210628
Luis O. Pimentel, Flavio PinedaIn this work we consider particle creation by the expansion of the universe, using two Bianchi type I anisotropic models. The particles studied are of spin 0 and 1/2. The cosmological models have rotational symmetry, which allows us to solve exactly the equations of motion. The number density of the created particles is calculated with the method of Bogolubov transformations.

Spacetimes with continuous linear isotropies II: boosts Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210622
M. A. H. MacCallumConditions are found which ensure that local boost invariance (LBI), invariance under a linear boost isotropy, implies local boost symmetry (LBS), i.e. the existence of a local group of motions such that for every point P in a neighbourhood there is a boost leaving P fixed. It is shown that for Petrov type D spacetimes this requires LBI of the Riemann tensor and its first derivative. That is also true

Static cosmological solutions in quadratic gravity Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210621
Daniel Müller, Alexey ToporenskyWe consider conditions for existence and stability of a static cosmological solution in quadratic gravity. It appears that such a solution for a Universe filled by only one type of perfect fluid is possible in a wide range of the equation of state parameter w and for both positively and negatively spatially curved Universe. We show that the static solution for the negative curvature is always unstable

The evolution of binary neutron star postmerger remnants: a review Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210612
Nikhil Sarin, Paul D. LaskyTwo neutron stars merge somewhere in the Universe approximately every 10 to 100 s, creating violent explosions potentially observable in gravitational waves and across the electromagnetic spectrum. The transformative coincident gravitationalwave and electromagnetic observations of the binary neutron star merger GW170817 gave invaluable insights into these cataclysmic collisions, probing bulk nuclear

Galactic clustering under powerlaw modified newtonian potential Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210610
Abdul W. Khanday, Sudhaker Upadhyay, Prince A. GanaiWe estimate galaxy clustering under a modified gravitational potential. In particular, the modifications in gravitational potential energy occur due to a powerlaw and cosmological constant terms. We derive a canonical partition function for the system of galaxies interacting under such a modified gravitational potential. Moreover, we compute various thermodynamical equation of states for the system

Spacetimes with continuous linear isotropies I: spatial rotations Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210609
M. A. H. MacCallumThe weakest known criterion for local rotational symmetry (LRS) in spacetimes of Petrov type D is due to Goode and Wainwright (Gen Rel Grav 18:315, 1986). Here it is shown, using methods related to the CartanKarlhede procedure, to be equivalent to local spatial rotation invariance of the Riemann tensor and its first derivatives. Conformally flat spacetimes are similarly studied and it is shown that

Retraction Note to: Letter: On a SemiNumeric Method to Study the Evolution of a GeneralRelativistic Radiating Shell and XRay Bursters Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210528
Roberto AquilanoA correction to this paper has been published: https://doi.org/10.1007/s1071402102825z

Quantum phase space description of a cosmological minimal massive bigravity model Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210526
Julio César VeraHernándezBimetric gravity theories describes gravitational interactions in the presence of an extra spin2 field. The Hassan–Rosen (HR) nonlinear massive minimal bigravity theory is a ghostfree bimetric theory formulated with respect a flat, dynamical reference metric. In this work the deformation quantization formalism is applied to a HR cosmological model in the minisuperspace. The quantization procedure

On gravitational StefanBoltzmann law and Casimir effect in FRW universe Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210524
A. F. Santos, S. C. Ulhoa, E. P. Spaniol, Faqir C. KhannaBoth StefanBoltzmann law and the Casimir effect, in a universe described by the FRW metric with zero curvature, are calculated. These effects are described by Thermo Field Dynamics (TFD). The gravitational energymomentum tensor is defined in the context of Teleparallel Equivalent to General Relativity (TEGR). Each of the two effects gives a consistent prediction with what is observed on a cosmological

Magnetogenesis in Higgs inflation Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210514
Mehran KamarpourWe study the generation of magnetic fields in the Higgs inflation model with the axial coupling in order to break the conformal invariance of the Maxwell action and produce strong enough magnetic fields for observed largescale magnetic fields. This interaction breaks the parity and enables a production of only one of the polarization states of the electromagnetic field due to axionlike coupling of

Straightforward Hamiltonian analysis of BF gravity in n dimensions Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210507
Merced Montesinos, Ricardo Escobedo, Mariano CeladaWe perform, in a manifestly \(\mathrm{SO}(n1,1)\) [\(\mathrm{SO}(n)\)] covariant fashion, the Hamiltonian analysis of general relativity in n dimensions written as a constrained BF theory. We solve the constraint on the B field in a way naturally adapted to the foliation of the spacetime that avoids explicitly the introduction of the vielbein. This leads to a form of the action involving a presymplectic

Aspects of GRMHD in highenergy astrophysics: geometrically thick disks and tori agglomerates around spinning black holes Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210430
D. Pugliese, G. MontaniThis work focuses on some key aspects of the general relativistic (GR)—magnetohydrodynamic (MHD) applications in highenergy astrophysics. We discuss the relevance of the GRHD counterparts formulation exploring the geometrically thick disk models and constraints of the GRMHD shaping the physics of accreting configurations. Models of clusters of tori orbiting a central supermassive black hole (SMBH)

Weak gravitational quantum effects in boson particles Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210428
Omar Gallegos, Tonatiuh MatosWe rewrite the Klein–Gordon equation in an arbitrary spacetime transforming it into a generalized Schrödinger equation. Then, we take the weak field limit and show that this equation has certain differences with the traditional Schrödinger equation plus a gravitational field. Thus, this procedure shows that the Schrödinger equation derived in a covariant manner is different from the traditional one

Dark matter and torsion Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210427
G. GrensingSuperheavy righthanded Majorana neutrinos are proposed as a promising candidate for dark matter, with dynamical axial torsion as the mediating agent.

Dynamics of nonminimally coupled scalar field models with generic potentials in FLRW background Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210426
M. Shahalam, Shynaray MyrzakulWe study the phase space analysis of a nonminimally coupled scalar field model with generic potentials such as KKLT, Higgs, inverse and inverse square. Our investigation brings new asymptotic regimes, and obtains stable deSitter solution. In case of KKLT, we do not find stable deSitter solution whereas Higgs model satisfies the deSitter condition but does not provide a stable deSitter solution

Photon helicity and quantum anomalies in curved spacetimes Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210426
Matteo Galaverni, Gionti, S. J. GabrieleWe compare several definitions of photon helicity (magnetic, electric, electromagnetic) present in literature. In curved spacetime quantum anomalies can spoil helicity conservation inducing  according to these definitions  different effects on photons: either rotation of linear polarization or production of circular polarization. We derive the Noether current associated with duality transformations

Exploring the new Tsallis agegraphic dark energy with interaction through statefinder Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210426
Shikha Srivastava, Umesh Sharma, Vipin DubeyIn this work, we explore the recently proposed new Tsallis agegraphic dark energy model in a flat FLRW Universe by taking the conformal time as IR cutoff with interaction. The deceleration parameter of the interacting new Tsallis agegraphic dark energy model provides the phase transition of the Universe from decelerated to accelerated phase. The EoS parameter of the model shows a rich behaviour as

Doubly torqued vectors and a classification of doubly twisted and Kundt spacetimes Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210426
Carlo Alberto Mantica, Luca Guido MolinariThe simple structure of doubly torqued vectors allows for a natural characterization of doubly twisted down to warped spacetimes, as well as Kundt spacetimes down to PP waves. For the first ones the vectors are timelike, for the others they are null. We also discuss some properties, and their connection to hypersurface orthogonal conformal Killing vectors, and null Killing vectors.

The problem of motion in gauge theories of gravity Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210423
Serhii SamokhvalovIn this article we consider the problem to what extent the motion of gaugecharged matter that generates the gravitational field can be arbitrary, as well as what equations are superimposed on the gauge field due to conditions of compatibility of gravitational field equations. Considered problem is analyzed from the point of view symmetry of the theory with respect to the generalized gauge deformed

Modified Hawking radiation of stationary and nonstationary Kerr–Newman–de Sitter black hole Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210422
S. Christina, T. Ibungochouba SinghIn this paper, the tunneling of vector boson particles across the event horizon of Kerr–Newman–de Sitter (KNdS) black hole is investigated using the WKB approximation and Hamilton–Jacobi ansatz to Proca equation. The tunneling probability and radiation spectrum at the event horizon of KNdS black hole is obtained. The modified Hawking radiation of stationary and nonstationary KNdS black hole are also

Multidomain GalerkinCollocation method: characteristic spherical collapse of scalar fields Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210421
M. A. Alcoforado, W. O. Barreto, H. P. de OliveiraWe initiate a systematic implementation of the spectral domain decomposition technique with the GalerkinCollocation method in situations of interest such as the spherical collapse of a scalar field in the characteristic formulation. We discuss the transmission conditions at the interface of contiguous subdomains that are crucial for the domain decomposition technique for hyperbolic problems. We implemented

Finite Tsallis gravitational partition function for a system of galaxies Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210418
Mir Hameeda, B. Pourhassan, M. C. Rocca, Mir FaizalIn this paper, we will study the large scale structure formation using the gravitational partition function. We will assertively argue that the system of gravitating galaxies can be analyzed using the Tsallis statistical mechanics. The divergences in the Tsallis gravitational partition function can be removed using the mathematical riches of the generalization of the dimensional regularization (GDR)

Black holes, Planckian granularity, and the changing cosmological ‘constant’ Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210417
Alejandro Perez, Daniel SudarskyIn a recent work we have argued that noisy energy momentum diffusion due to spacetime discreteness at the Planck scale (naturally expected to arise from quantum gravity) can be responsible for the generation of a cosmological constant at the electroweak phase transition era of the cosmic evolution. Simple dimensional analysis and an effectively Brownian description of the propagation of fundamental

A model of spinfoam coupled with an environment Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210416
Quentin AnselIn this paper, an open quantum system theory for spinfoams is developed. This new formalism aims at deriving an effective Lindblad equation to compute the reduced dynamics of a quantum gravitational field. The system parameters are determined from numerical ab initio calculations, based on the spinfoam formalism. This theoretical proposal is illustrated by means of examples. The decoherence effect

Universality of the spherical collapse with respect to the matter type: the case of a barotropic fluid with linear equation of state Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210412
François Staelens, Jérémy Rekier, André FüzfaWe study the spherical collapse of an overdensity of a barotropic fluid with linear equation of state in a cosmological background. Fully relativistic simulations are performed by using the Baumgarte–Shibata–Shapiro–Nakamura formalism jointly with the Valencia formulation of the hydrodynamics. This permits us to test the universality of the critical collapse with respect to the matter type by considering

A study of space–time variation of the gravitational constant using highresolution quasar spectra Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210408
T. D. LeThe possibility of motivational probes variations in dimensionless fundamental constants like the finestructure constant, the protontoelectron mass ratio, and the gravitational constant could provide a significant test of grand unification theories (GUTs). The best way of probing these variations would be based on quasar absorption lines, which allow to test them directly at any regions or epochs

A classification theorem for compact Cauchy horizons in vacuum spacetimes Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210325
Ignacio Bustamante, Martín ReirisWe establish a complete classification theorem for the topology and for the orbital type of the null generators of compact nondegenerate Cauchy horizons of time orientable smooth vacuum \(3+1\)spacetimes. We show that one and only one of the following must hold: (i) all generators are closed, (ii) only two generators are closed and any other densely fills a twotorus, (iii) every generator densely

Phase transitions in D dimensional Gauss–Bonnet–Born–Infeld AdS black holes Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210324
Neeraj Kumar, Sunandan GangopadhyayIn this paper, we have investigated the phase transition in black holes when Gauss–Bonnet corrections to the spacetime curvature and Born–Infeld extension in stress–energy tensor of electromagnetic field are considered in a negative cosmological constant background. It is evident that the black hole undergoes a phase transition as the specific heat capacity at constant potential shows discontinuities

Generalizing Birkhoff Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210320
Joel L. WeinerWe generalize Birkhoff’s Theorem in the following fashion. We find necessary and sufficient conditions for any spherically symmetric spacetime to be static in terms of the eigenvalues of the stressenergy tensor. In particular, we generalize the Tolman–Oppenheimer–Volkoff equation and prove that Birkhoff’s theorem holds under the weaker hypothesis of no pressure (with respect to an appropriate frame

Chern–Simons extension of ESK theory Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210315
Luca FabbriThe commonlyknown Chern–Simons extension of Einstein gravitational theory is written in terms of a squarecurvature term added to the linearcurvature Hilbert Lagrangian. In a recent paper, we constructed two Chern–Simons extensions according to whether they consisted of a squarecurvature term added to the squarecurvature Stelle Lagrangian or of one linearcurvature term added to the linearcurvature

Wheeler–DeWitt quantization for pointparticles Gen. Relativ. Gravit. (IF 2.513) Pub Date : 20210311
Ward StruyveWe present the Hamiltonian formulation of a relativistic pointparticle coupled to Einstein gravity and its canonical quantization à la Wheeler–DeWitt. In the resulting quantum theory, the wave functional is a function of the particle coordinates and the 3metric. It satisfies a particular Hamiltonian and diffeomorphism constraint, together with a Klein–Gordontype equation. As usual in the Wheeler–DeWitt