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Cosmological Evolution of a Scalar-Charged Degenerate Cosmological Plasma with Higgs Scalar Fields Gravit. Cosmol. (IF 0.88) Pub Date : 2020-12-07 Yu. G. Ignat’ev
Abstract A mathematical model of the cosmological evolution of statistical systems of scalarly charged particles with Higgs scalar interaction is formulated and investigated. Examples are given of numerical modeling of such systems, revealing their very remarkable properties, in particular, the formation of paired bursts of cosmological acceleration.
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A Model of the Big Bang and Universe Expansion in General Relativity with Spread of a Gas Mass from a Point to Empty Space Gravit. Cosmol. (IF 0.88) Pub Date : 2020-12-07 A. N. Kraiko
Abstract A new model is constructed for the Big Bang and the expansion of the Universe, based on a description of a spread of a finite mass of ideal (nonviscous and non-heat-conducting) gas from a point (“initial hot singularity”) to empty space in the framework of general and special relativity (GR and SR). That is, the expansion began inside the sphere with the gravitational radius of the Universe
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Early Inflationary Phase with Canonical and Noncanonical Scalar Fields: A Symmetry-Based Approach Gravit. Cosmol. (IF 0.88) Pub Date : 2020-12-07 Mithun Bairagi, Amitava Choudhuri
Abstract We study the early inflationary phase of the universe driven by noncanonical scalar field models using an exponential potential. The noncanonical scalar field models are represented by Lagrangian densities containing square and square-root kinetic corrections to the canonical Lagrangian density. We investigate the Lie symmetry of the homogeneous scalar field equations obtained from noncanonical
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Constraints from Observational Data for a Running Cosmological Constant and Warm Dark Matter with Curvature Gravit. Cosmol. (IF 0.88) Pub Date : 2020-12-07 Jhonny A. Agudelo Ruiz, Júlio C. Fabris, Alan M. Velasquez-Toribio, Ilya L. Shapiro
Abstract It is known than the inclusion of spatial curvature can modify the evolution of matter perturbations and affect the Large Scale Structure (LSS) formation. We quantify the effects of the nonzero spatial curvature in terms of LSS formation for a cosmological model with a running vacuum energy density and a warm dark matter component. The evolution of density perturbations and the modified shape
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Mass Generation by a Massless Scalar Field Gravit. Cosmol. (IF 0.88) Pub Date : 2020-12-07 A. P. Lelyakov
Abstract We propose a possibility of qualitatively taking into account the mutual influence of two gravitationally interacting null strings (thin tubes of a massless scalar field) on the motion of each of them. It is shown that it is possible to implement a self-consistent motion of two null strings in which their mutual gravitational influence leads to vibrations of each string inside a bounded spatial
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Dynamical System Study of Nonminimal Tachyon Field within Holographic Cosmology Gravit. Cosmol. (IF 0.88) Pub Date : 2020-12-07 Farida Bargach, Aatifa Bargach, Taoufik Ouali
Abstract We use the dynamical system method in order to investigate the dynamics of a non-minimally coupled tachyon field within induced gravity on the brane in a holographic cosmological context. Assuming an exponential potential and a monomial form of the nonminimal coupling function, we construct the phase space of the model. Two possible cases, namely, the minimal and nonminimal coupling, are investigated
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Scalar Perturbations of Galileon Cosmologies in the Mechanical Approach within the Late Universe Gravit. Cosmol. (IF 0.88) Pub Date : 2020-12-07 Jan Novák
Abstract We investigate the Universe at the late stage of its evolution and inside the cell of uniformity, 150–370 Mpc. We consider the Universe to be filled at these scales with dustlike matter, a minimally coupled Galileon field and radiation. We use the mechanical approach. Therefore, the peculiar velocities of the inhomogeneities as well as the fluctuations of other perfect fluids can be considered
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The Second Post-Newtonian Motion in Schwarzschild Spacetime Gravit. Cosmol. (IF 0.88) Pub Date : 2020-12-07 Bo Yang, Wenbin Lin
Abstract We present the second-order post-Newtonian solution for the quasi-Keplerian motion in the Schwarzschild space-time under the Wagoner-Will-Epstein-Haugan representation. Detailed derivations are provided for readers’ convenience.
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Nonzero Gravitational Force Exerted by a Spherical Shell on a Body Moving Inside It, and Cosmological Implications Gravit. Cosmol. (IF 0.88) Pub Date : 2020-12-07 F. M. S. Lima
Abstract The shell theorem, proved by Newton in his Principia (1687), states that the net force exerted by a uniform spherical shell on a body located anywhere inside it is zero, as long as the force is proportional to the inverse square of the distance between the interacting bodies. This null result remains valid whenever the interaction depends only on the distance between the bodies, but not on
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Lambda Perturbations of Keplerian Orbits in the Expanding Universe Gravit. Cosmol. (IF 0.88) Pub Date : 2020-12-07 Yu. V. Dumin
Abstract To estimate the influence of “dark energy” on Keplerian orbits, we solve the general-relativistic equations of motion of a test particle in the field of a pointlike mass embedded in the cosmological background formed by the cosmological constant with realistic cosmological Robertson–Walker asymptotics at infinity. It is found that under certain relations between three crucial parameters of
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Constraining $$\boldsymbol{f(R,T)}$$ Gravity from the Dark Energy Density Parameter $$\boldsymbol{\Omega}_{\boldsymbol{\Lambda}}$$ Gravit. Cosmol. (IF 0.88) Pub Date : 2020-09-21 Snehasish Bhattacharjee, P. K. Sahoo
Abstract \(f(R,T)\) gravity is a widely used extended theory of gravity introduced by Harko et al., which is a straightforward generalization of \(f(R)\) gravity. The action in this extended theory of gravity incorporates well-motivated functional forms of the Ricci scalar \(R\) and the trace of the energy momentum tensor \(T\). The present manuscript aims at constraining the most widely used \(f(R
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Hamiltonian Equations of Reduced Conformal Geometrodynamics in Extrinsic Time Gravit. Cosmol. (IF 0.88) Pub Date : 2020-09-21 A. E. Pavlov
Abstract The reduced vacuum Hamiltonian equations of conformal geometrodynamics of compact manifolds in extrinsic time are written. This is achieved by generalizing the theorem of implicit function derivative to the functional analysis. Under the assumption that constant curvature slicing takes place, York’s field time becomes the global time.
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One-Loop Effective Action: Nonlocal Form Factors and Renormalization Group Gravit. Cosmol. (IF 0.88) Pub Date : 2020-09-21 Poliane de Morais Teixeira, Ilya L. Shapiro, Tiago G. Ribeiro
Abstract We review and present full details of the Feynman diagram based and the heat-kernel method based calculations of the simplest nonlocal form factors in the one-loop contributions of a massive scalar field. The paper has pedagogical and introductory purposes and is intended to help the reader in better understanding the existing literature on the subject. The functional calculations are based
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Interacting Holographic Dark Energy, the Present Accelerated Expansion and Black Holes Gravit. Cosmol. (IF 0.88) Pub Date : 2020-09-21 Bibekananda Nayak
Abstract We study the evolution of the universe by assuming an integrated model, which involves interacting dark energy and the holographic principle with the Hubble scale as an IR cutoff. First we determine the interaction rate at which matter is converting to dark energy. At the next step, we evaluate the equation of state parameter which describes the nature of dark energy. Our result predicts that
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Spinning Equations for Objects of Some Classes in Finslerian Geometry Gravit. Cosmol. (IF 0.88) Pub Date : 2020-09-21 Magd E. Kahil
Abstract Spinning equations of Finslerian gravity, the counterpart of the Mathisson-Papapetrou spinning equations of motion are obtained. Two approaches of Finslerian geometries are formulated and discussed, the Cartan-Rund and Finsler-Cartan ones, as well as their corresponding spinning equations. The significance of the nonlinear connection and its relevance on spinning equations is noticed, and
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Nature of Higher-Dimensional Wormhole Mass Due to Accretion of Entropy Corrected Holographic and New Agegraphic Dark Energies Gravit. Cosmol. (IF 0.88) Pub Date : 2020-09-21 Ujjal Debnath, Soumyadipta Basak
Abstract We study the accretion of dark matter and dark energy onto \((n+2)\)-dimensional Morris–Thorne wormholes. The wormhole mass and its rate of change have been written in the background of the \((n+2)\)-dimensional Friedmann-Robertson-Walker (FRW) model of the Universe. We have assumed the candidates of dark energy in the form of entropy-corrected holographic dark energy (ECHDE) and entropy-corrected
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Cosmological Density Perturbations from Matter Domination to Recombination in Newtonian and MONDian Gravity Scenarios Gravit. Cosmol. (IF 0.88) Pub Date : 2020-09-21 Aritra Ganguly, Amitava Choudhuri
Abstract Cosmological density perturbations governed by Newtonian and MONDian force laws scenarios for the period from matter domination to recombination have been investigated. Particularly, we find solutions for the density contrast equations obtained for both cases with respect to a homogeneous spatially flat Friedman-Lemaître-Robertson-Walker (FLRW) background using the Lie symmetry approach. Numerical
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Thermodynamic Properties of a Yukawa–Schwarzschild Black Hole in Noncommutative Gauge Gravity Gravit. Cosmol. (IF 0.88) Pub Date : 2020-09-21 Slimane Zaim, Hadjar Rezki
Abstract We construct a noncommutative gauge theory for the deformed metric corresponding to the modified structure of a gravitational field in the case of noncommutative Yukawa–Schwarzschild space-time. The thermodynamic properties and corrections t o the gravitational force on the horizon of a noncommutative Yukawa–Schwarzschild black hole are analyzed.
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Cosmological Inflation Based on the Uncertainty-Mediated Dark Energy Gravit. Cosmol. (IF 0.88) Pub Date : 2020-09-21 Yu. V. Dumin
Abstract It was suggested in our previous paper [Yu.V. Dumin, Grav. Cosmol. 25, 169 (2019)] that the cosmological Dark Energy might be mediated by the time–energy uncertainty relation in the Mandelstam–Tamm form, which is appropriate for the long-term evolution of quantum systems. The amount of such Dark Energy gradually decays with time, and the corresponding scale factor of the Universe increases
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Axially Symmetric Type N Space-Time with Causality Violating Curves and the von Zeipel Cylinder Gravit. Cosmol. (IF 0.88) Pub Date : 2020-09-21 Faizuddin Ahmed
Abstract An axially symmetric nonvacuum solution of the Einstein field equations, regular everywhere and free from curvature divergence is presented. The matter-energy content is a the pure radiation field satisfying the energy conditions, and the metric is of type N in the Petrov classification scheme. The space-time develops circular closed timelike curves everywhere outside a finite region of space
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Short-Wave Approximation for Macroscopic Cosmology with Higgs Scalar Field Gravit. Cosmol. (IF 0.88) Pub Date : 2020-09-21 Yu. G. Ignat’ev, D. Yu. Ignat’ev
Abstract Based on the macroscopic equations of cosmological evolution obtained earlier by the author, a closed set of macroscopi Einstein equations in the short-wave approximation for perturbations of the scalar Higgs and gravitational fields has been obtained and examined. The resulting exact solutions of the macroscopic equations are determined by three microscopic parameters, depending on the spectrum
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Hybrid Metric-Palatini Gravity: Black Holes, Wormholes, Singularities, and Instabilities Gravit. Cosmol. (IF 0.88) Pub Date : 2020-09-21 K. A. Bronnikov, S. V. Bolokhov, M. V. Skvortsova
Abstract The hybrid metric-Palatini theory of gravity (HMPG), proposed in 2012 by T. Harko et al., is known to successfully describe both local (solar-system) and cosmological observations. We discuss static, spherically symmetric vacuum solutions of HMPG with the aid of its scalar-tensor theory (STT) representation. This scalar-tensor theory coincides with general relativity with a conformally coupled
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Properties of the Vlasov–Maxwell–Einstein Equations and Their Application to the Problems of General Relativity Gravit. Cosmol. (IF 0.88) Pub Date : 2020-08-22 V. V. Vedenyapin; N. N. Fimin; V. M. Chechetkin
AbstractA new universal method is proposed for obtaining Vlasov–type equations for systems of interacting massive charged particles from the general-relativistic Einstein–Hilbert action. At the same time, a new effective approach to synchronizing the proper times of various particles of a many–particle system has been introduced. A new form of the energy–momentum tensor for matter (and the right-hand
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Galactic Rotation Curves in Conformal Scalar-Tensor Gravity Gravit. Cosmol. (IF 0.88) Pub Date : 2020-08-22 Qiang Li; Leonardo Modesto
AbstractWe show quantitatively that an exact solution of conformal scalar-tensor gravity can explain very well the galactic rotation curves for a sample of 104 galaxies without the need for dark matter or other exotic modification of gravity. The metric is an overall rescaling of the Schwarzschild-de Sitter space-time as required by Weyl conformal invariance, which has to be spontaneously broken, and
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Cosmological Solutions in the Tensor-Multi-Scalar Theory of Gravity with the Higgs Potential Gravit. Cosmol. (IF 0.88) Pub Date : 2020-08-22 K. A. Bolshakova; S. V. Chervon
AbstractWe consider a generalization of Higgs inflation, based on cosmology of general relativity (GR), to the case of a two-field model of the tensor-multiscalar theory of gravity (TMS TG). Cosmological solutions are found in the case where a scalar field with the Higgs potential, as a source of TMS TG is in the slow-rolling mode. Solutions with power and exponential-power-law evolution of the scale
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Sensitivity of the Gravity Assist to Variations of the Impact Parameter Gravit. Cosmol. (IF 0.88) Pub Date : 2020-08-22 A. P. Yefremov
AbstractWe build a Kepler model of spacecraft gravity assist maneuver near a Venus-type planet and investigate its sensitivity to changes of the impact parameter. Analytical and numerical computations give similar results indicating a great increase of the trajectory final point shift under a small variation of the assigned spacecraft-planet distance.
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Finding Integrals and Identities in the Newman–Penrose Formalism: a Comment Gravit. Cosmol. (IF 0.88) Pub Date : 2020-08-22 G. O. Papadopoulos
AbstractThe goal of the present short letter is to prove, through a specific example (i.e., the class of Ricci-flat, Petrov type D geometries), that the original Newman-Penrose (NP) formalism, seen as an exterior differential system (EDS), suffices to provide the needed syzygies and integrals of the EDS under consideration—without (in principle) the aid of a computer algebra system (CAS).
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The Effect of Interplay between the Newtonian Gravitational Field and the Cosmological Expansion Gravit. Cosmol. (IF 0.88) Pub Date : 2020-08-22 A. Feoli; E. Benedetto; A. L. Iannella
AbstractWe study the motion of a celestial body under the simultaneous effect of the Newtonian and cosmological fields. The resulting effect is not only interesting by itself, but it could also give a contribution to solving the well-known problem of galactic rotation curves without the assumption of the existence of dark matter. We assume that in the outer regions of galaxies the stars and the hydrogen
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Axially Symmetric Type N Space-Time with a Naked Curvature Singularity and Closed Timelike Curves Gravit. Cosmol. (IF 0.88) Pub Date : 2020-08-22 Faizuddin Ahmed
AbstractA family of type N exact solutions of the Einstein field equations, regular everywhere except on the symmetry axis, where it possesses a naked curvature singularity, is presented. The stress-energy tensor is that of an anisotropic fluid coupled with a pure radiation field and satisfies different energy conditions, and the physical parameters diverge as \(r\to 0\). The space-time admits a non-expanding
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Accelerating Model of a Flat Universe in $$\boldsymbol{f(R,T)}$$ Gravity Gravit. Cosmol. (IF 0.88) Pub Date : 2020-08-22 Nishant Singla; Mukesh Kumar Gupta; Anil Kumar Yadav
AbstractThe \(f(R,T)\) theory of gravity is an extended theory of gravity in which the gravitational action contains both the Ricci scalar \(R\) and the trace of the energy-momentum tensor \(T\), and hence the cosmological models based on \(f(R,T)\) gravity are eligible to describing the late-time acceleration of the present universe. In this paper, we investigate an accelerating model of a flat universe
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Statistical Physics and Thermodynamics of Processes in General Relativity Gravit. Cosmol. (IF 0.88) Pub Date : 2020-08-22 A. L. Krugly
AbstractA model of a relativistic process as a finite set of elementary events is considered. General properties of statistics of elementary events are considered. The model has the following properties. Any macroscopic property of any process is a consequence of this statistics. The least action principle means that a macroscopic process chooses a variant with maximum probability. A massive particle
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Compensation of Atmospheric Hindrances in Measuring the Gravitational Redshift Using Satellites On-board Clocks Gravit. Cosmol. (IF 0.88) Pub Date : 2020-08-22 A. V. Belonenko; S. M. Popov; V. N. Rudenko
AbstractThe possibility of compensating the atmospheric influence on precision measurement of gravitational ‘‘redshift’’ using the Earth orbiting satellites is discussed. For a communication radio signal propagating from a ground-based tracking station to a spacecraft and back, the interaction with the ionosphere and the troposphere produces a undesirable contribution to the total frequency shift which
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The Kerr–Newman Black Hole Solution as Strong Gravity for Elementary Particles Gravit. Cosmol. (IF 0.88) Pub Date : 2020-08-22 A. Burinskii
AbstractAnalyzing the model of a spinning particle based on the over-rotating Kerr–Newman solution regularized by a supersymmetric bag model, we arrive at the conclusion that a unification of gravity with quantum theory is achieved in this model due to a strong topological influence of the Kerr spinning gravity which occurs on the Compton scale. We obtain that the correct formation of the nonperturbative
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First Law of Black Hole Thermodynamics for the Kerr–Newman Spacetime Using Foliation Gravit. Cosmol. (IF 0.88) Pub Date : 2020-05-26 Syed Muhammad Jawwad Riaz; Azad A. Siddiqui
AbstractThis article follows a simpler approach (Siddiqui et al. 2011) using the foliation concept with virtual displacement of hypersurfaces near the event horizon to derive the first law of black hole thermodynamics for the Kerr–Newman black hole spacetime.
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Evaluation of the Anomalous Force Detected in the Datta, Yin and Vargas Experiment, According to Mbelek and Lachièze-Rey Scalar-Tensor Theory of Gravitation Gravit. Cosmol. (IF 0.88) Pub Date : 2020-05-26 F. O. Minotti
AbstractAn analysis is presented of the experiment by Datta, Yin and Vargas in the light of the Mbelek–Lachièze-Rey scalar-tensor theory of gravitation, showing that this theory reproduces the magnitude and sign of the measured anomalous weight increment of conducting balls immersed in an inhomogeneous electric field.
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Temperature of Interstellar Space Revisited by Relational Approach Gravit. Cosmol. (IF 0.88) Pub Date : 2020-05-26 A. B. Molchanov
AbstractThe article features an interpretation of the cosmic microwave background (CMB) radiation in the framework of the relational approach. The key concept of the proposed interpretation is strongly connected with the ideas on the ‘‘temperature of interstellar space’’ put forward by Weyl, Eddington, Regener and Nernst in the 1920s–1930s. In accordance with the relational justification of the cosmological
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On Stability of Exponential Cosmological Type Solutions with Two Factor Spaces in the Einstein–Gauss–Bonnet Model with a $$\boldsymbol{\Lambda}$$ -Term Gravit. Cosmol. (IF 0.88) Pub Date : 2020-05-26 V. D. Ivashchuk
AbstractWe study a \(D\)-dimensional Einstein–Gauss–Bonnet gravitational model including the Gauss-Bonnet term and the cosmological constant \(\Lambda\). We find a class of cosmological type solutions with exponential dependence of two scale factors on the variable \(u\) (either cosmological time or a spatial coordinate), governed by two Hubble-like parameters \(H\neq 0\) and \(h\), corresponding to
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Can Weak Field Lensing Distinguish Between a Naked Singularity, an Ellis-Bronnikov Regular Wormhole and a Black Hole? Gravit. Cosmol. (IF 0.88) Pub Date : 2020-05-26 R. N. Izmailov; R. F. Lukmanova
AbstractThe purpose of this paper is to investigate if the weak field lensing (WFL) observables can distinguish between three physically distinct lenses, mathematically connected by a combination of real and complex transformations. All three kinds of lenses have been discussed in the literature in the strong field limit, but since the weak field light deflection does not follow as a PPN expansion
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Accretion of Some Classes of Holographic DE onto Higher-Dimensional Schwarzschild Black Holes Gravit. Cosmol. (IF 0.88) Pub Date : 2020-05-26 Ujjal Debnath
AbstractWe study the accretion of dark matter and DE onto \((n+2)\)-dimensional Schwarzschild black holes. Since, due to the accretion process, the mass of the black hole is dynamical, so the mass and its changing rate for \((n+2)\)-dimensional Schwarzschild black holes have been found. We assume a general form of holographic DE where the dimensionless model parameter \(c\) is assumed to be variable
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Electromagnetic Origin of Particle Masses and Gravity: a Relativistic Theory Gravit. Cosmol. (IF 0.88) Pub Date : 2020-05-26 M. Yu. Romashka
AbstractThe theory of direct particle interaction proposed in our previous works is further developed. In this theory, the electromagnetic interaction is primary whereas the emergence of particle masses and gravity are its consequences. The equation of motion is generalized to arbitrary velocities of the selected particle (rather than small ones). With the introduction of an effective metric, a correspondence
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Velocities of Distant Objects in General Relativity Revisited Gravit. Cosmol. (IF 0.88) Pub Date : 2020-05-26 E. D. Emtsova; A. V. Toporensky
AbstractWe consider two most popular definitions of velocities of remote objects in General Relativity. Our work has two motivations. From a research point of view, we generalize the formula connecting these two velocities in FRW metrics found by Chodorowski to arbitrary synchronous spherically symmetric metrics. From a methodological point of view, our goal is to outline certain counter-intuitive
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Bianchi–III Transitioning Space-Time in a Nonsingular Hybrid Universe within Lyra’s Cosmology Gravit. Cosmol. (IF 0.88) Pub Date : 2020-05-26 Vinod Kumar Bhardwaj; Manoj Kumar Rana
AbstractThe existence of Lyra’s cosmology is studied with the least interaction between normal matter and dark energy using Bianchi-III space-time in a nonsingular hybrid universe. The model explains the phase transition of the universe from deceleration to acceleration in the presence of a perfect fluid and naturewise anisotropic dark energy interacting very minimally to keep the energy-momentum tensors
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Massive Gravity as an Alternative Gravity Gravit. Cosmol. (IF 0.88) Pub Date : 2020-05-26 Y. Sobouti
AbstractThe Newtonian gravity force is massless and decreases as \(1/r^{2}\), too steeply to explain the flat rotation curves of spiral galaxies. Massive gravity, on the other hand, drops as \(1/r\) and is capable of doing the job. Massive fields have a respected record in the history of field theories. We follow the suit and add a ‘‘mass term’’ to the field equation of Newtonian gravity, which, to
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A Complete Model of Cosmological Evolution of a Scalar Field with Higgs Potential and Euclidean Cycles Gravit. Cosmol. (IF 0.88) Pub Date : 2020-05-26 Yu. G. Ignat’ev; D. Yu. Ignat’ev
AbstractA revision of the author’s results concerning the possible existence of the so-called Euclidean cycles in cosmological evolution of a system of Higgs scalar fields is being performed. The assumption of a nonnegative velocity of the Universe expansion, which in certain cases contradicts the complete set of the Einstein equations, is removed. It is shown that in the cases where the effective
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Entangled Gravitons? Prospective Original Scenarios in Cosmology Gravit. Cosmol. (IF 0.88) Pub Date : 2020-05-26 Ara K. Avetissian
AbstractBeing convinced in global generalities of Nature’s fundamental principles, phenomena and processes on all cosmic scales, and taking a broad view on the phenomenon of photons’ entanglement, here one postulates the phenomenon of large-scale entanglement of gravitons. This original phenomenon might play a major role in justifying the networks of galaxies and their clusters. The mechanism of entangled
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Wave Function of the Universe, Path Integrals and Gauge Invariance Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 T. P. Shestakova
—The paper is devoted to some of the difficulties which the Wheeler-DeWitt quantum geometrodynamics encountered, in particular, a strong mathematical proof that this theory is gauge-invariant, the definition of the wave function of the Universe through a path integral and the illegality of asymptotic boundary conditions in quantum gravity, the derivation of the Wheeler-DeWitt equation from the path
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Dark Matter Particles: Properties and Detections Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 Salah Eddine Ennadifi; Karim Douhou
One of the most accepted ideas in modern cosmology to explain a number of puzzling astronomical observations is the existence of Dark Matter in the Universe, even though it has not been directly observed. We recall the motivation for its existence according to its influence on visible matter and its characteristics in terms of famous candidate particles.
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Matrix Wheeler-DeWitt Equation, Quantum Cosmological Tunneling and Three-Dimensional Space Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 F. Gómez
To give a possible explanation of the 3-dimensionality of space, a matrix version of the Wheeler-DeWitt equation for quantum gravity is developed. In this equation, the number of spatial dimensions D is associated with a discrete variable. In this framework, a toy quantum-cosmological model for the birth of the universe from nothing is constructed. Here, nothing means a precosmic state with no classical
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Influence of the Gravitational Field of a Null String Domain on the Dynamics of a Test Null String Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 A. P. Lelyakov
The paper studies the influence of periodically changing boundary conditions on the motion of a test null string “inside” an axially symmetric null string domain that has a layered structure and preserves its size. It is shown that the action of the gravitational field of the null string domain on a test null string whose size (radius) is smaller than the size of the domain, under any initial conditions
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Weak-Field Limit of a Kaluza-Klein Model with a Nonlinear Perfect Fluid Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 Ezgi Yalçınkaya; Alexander Zhuk
The main purpose of our paper is to construct a viable Kaluza-Klein model satisfying the observational constraints. To this end, we investigate a six-dimensional model with spherical compactification of the internal space. Background matter is considered in the form of a perfect fluid with nonlinear equations of state both in the external/our and internal spaces, and the model is set to include an
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The Self-Consistent Field Method and the Macroscopic Universe Consisting of a Fluid and Black Holes Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 Yu. G. Ignat’ev
The article discusses and substantiates a self-consistent approach to the macroscopic description of systems with gravitational interaction. Corrections to the equation of state of the fluid are found, based on the macroscopic Einstein equations which were obtained by averaging over microscopic spherically symmetric metric fluctuations created by primordial black holes in a fluid medium. It is shown
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The Fractal Structure of Space Entails Origin of Pauli’s Equation Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 A. P. Yefremov
This study links the fractal structure of physical space-time to quantum-mechanical laws. It is shown that primitive distortions of the pregeometric surface, a fractal cell of 3D space, gives birth to a condition eliminating the metric defect while providing “eternal validity” of the exclusive algebras (of real, complex, and quaternion numbers). Written in the physical units typical for the micro-world
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Spherically Symmetric Black Holes and Wormholes in Hybrid Metric-Palatini Gravity Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 K. A. Bronnikov
The so-called hybrid metric-Palatini theory of gravity (HMPG), proposed in 2012 by T. Harko et al., is known to successfully describe both local (solar-system) and cosmological observations. This paper gives a complete description of static, spherically symmetric vacuum solutions of HMPG in the simplest case where its scalar-tensor representation has a zero scalar field potential V(ϕ), and both Riemannian
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What Can the Anthropic Principle Tell Us about the Future of the Dark Energy Universe Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 A. A. Yurova; A. V. Yurov; V. A. Yurov
An anthropic explanation of the evident smallness of the dark energy (DE) density value implies the existence of a time-dependent component of the scalar field, serving, together with a negative-valued cosmological constant, as one of two components to the overall DE density. The observers (i.e. us) might then only evolve in those regions of the universe where the sum of those two components (the positive
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Conservative Relativistic Algebrodynamics Induced on an Implicitly Defined World Line Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 Abdel Y. Chala; V. V. Kassandrov; N. V. Markova
In the framework of the Stueckelberg-Wheeler-Feynman concept of a “one-electron Universe” we consider a world line implicitly defined by a system of algebraic (precisely, polynomial) equations. A collection of pointlike “particles” of two kinds on the world line (or its complex extension) is defined by the real (complex conjugate) roots of the polynomial system and is detected then by an external inertial
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On the Description of Masses and Charges in the 6D Theory of Kaluza-Klein Type Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 Yu. S. Vladimirov; S. V. Bolokhov
We analyze two branches of five-dimensional theories from a methodological point of view: Kaluza’s theory and the Klein-Fock-Rumer (KFR) 5-optics, aimed at a geometric description of electromagnetism and masses of elementary particles, respectively. These two theories have a number of problematic points such as the Planckian masses in Kaluza’s theory, or appearing of a configuration space in the KFR
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Particle Creation in Friedmann–Robertson–Walker Universe Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 Özgür Sevinc; Ekrem Aydiner
Using variable gravitational and cosmological constants, the mechanism of particle creation in the universe is studied for Friedmann–Robertson–Walker (FRW) space-times at high dimensions to explain the early deceleration and present accelerating phases. To investigate the dynamics of these phases, we consider two scale factor of the forms \(a(t)=\sqrt{t^\alpha{e^t}}\) and \(a(t)=\sqrt[m]{{\rm{sin}}h(kt)}\)
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A Cosmological Scenario with Rotation Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 O. V. Sandakova; D. M. Yanishevsky; V. F. Panov
A Bianchi type IX cosmological model with expansion and rotation has been constructed in the framework of general relativity. The model comprises the Friedmannian stages of the Universe evolution including the subsequent transition to accelerated exponential expansion observed nowadays. The gravitational field sources of the model are ultrarelativistic matter, dust and a comoving anisotropic rotating
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Kinematic Censorship as a Constraint on Allowed Scenarios of High-Energy Particle Collisions Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 Yu. V. Pavlov; O. B. Zaslavskii
In the recent years, it was found that the energy Ec.m. in the center of mass frame of two colliding particles can be unbounded near black holes. If a collision occurs precisely on the horizon, Ec.m. is formally infinite. However, in any physically reasonable situation this is impossible. We collect different scenarios of this kind and show why in every act of collision Ec.m. is indeed finite (although
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Dyon-Like Black Hole Solutions in the Model with Two Abelian Gauge Fields Gravit. Cosmol. (IF 0.88) Pub Date : 2019-12-09 M. E. Abishev; V. D. Ivashchuk; A. N. Malybayev; S. Toktarbay
Dilatonic black hole dyon-like solutions are overviewed in the gravitational 4D model with a scalar field, two 2-forms, two dilatonic coupling constants λi ≠ 0, i = 1, 2, obeying λ1 ≠ − λ2, and the sign parameter ε = ±1 before the scalar field kinetic term. Here ε = −1 corresponds to a phantom scalar field. The solutions are defined up to solutions of two master equations for two moduli functions,
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