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10.0

Jun 30, 2018
06/18

by
Edward Anderson

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Wheeler emphasized the study of Superspace - the space of 3-geometries on a spatial manifold of fixed topology. This is a configuration space for GR; knowledge of configuration spaces is useful as regards dynamics and QM.In this Article I consider furthmore generalized configuration spaces to all levels within the conventional `equipped sets' paradigm of mathematical structure used in fundamental Theoretical Physics. This covers A) the more familiar issue of topology change in the sense of...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1412.0239

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4.0

Jun 30, 2018
06/18

by
Aleksandar Mikovic; Miguel A. Oliveira

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We find the canonical formulation of the Poincare BFCG theory in terms of the spatial 2-connection and its canonically conjugate momenta. We show that the Poincare BFCG action is dynamically equivalent to the BF action for the Poincare group and we find the canonical transformation relating the two. We study the canonical quantization of the Poincare BFCG theory by passing to the Poincare-connection basis. The quantization in the 2-connection basis can be then achieved by performing a Fourier...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1409.3751

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6.0

Jun 30, 2018
06/18

by
Pierre A. Mandrin

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Minimum information quantum gravity (MIQG) is a theory of quantum gravity which requires no explicit microscopic quantum structure. In this article, it is shown that the MIQG action can be derived using a more elegant and straight-forward method than in the first existence proof. The required assumptions are dramatically reduced. In particular, former assumptions referring to the existence of quantum boxes, the exact differential of the entropy variation and the role of the boundary can be...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1409.0809

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4.0

Jun 30, 2018
06/18

by
Tiberiu Harko; Matthew J. Lake

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We consider Kasner-type static, cylindrically symmetric interior string solutions in the $f\left(R,L_m\right)$ theory of modified gravity. The physical properties of the string are described by an anisotropic energy-momentum tensor satisfying the condition $T_t^t=T_z^z$; that is, the energy density of the string along the $z$-axis is equal to minus the string tension. As a first step in our study we obtain the gravitational field equations in the $f\left(R,L_m\right)$ theory for a general...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1409.8454

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4.0

Jun 30, 2018
06/18

by
Geoffrey Lovelace; Mark A. Scheel; Robert Owen; Matthew Giesler; Reza Katebi; Bela Szilagyi; Tony Chu; Nicholas Demos; Daniel A. Hemberger; Lawrence E. Kidder; Harald P. Pfeiffer; Nousha Afshari

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The spin angular momentum $S$ of an isolated Kerr black hole is bounded by the surface area $A$ of its apparent horizon: $8\pi S \le A$, with equality for extremal black holes. In this paper, we explore the extremality of individual and common apparent horizons for merging, rapidly spinning binary black holes. We consider simulations of merging black holes with equal masses $M$ and initial spin angular momenta aligned with the orbital angular momentum, including new simulations with spin...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1411.7297

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6.0

Jun 30, 2018
06/18

by
Donato Bini; Christian Cherubini; Andrea Geralico

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A single master equation is given describing spin $s\le2$ test fields that are gauge- and tetrad-invariant perturbations of the {\it spinning C metric} spacetime representing a source with mass $M$, uniformly rotating with angular momentum per unit mass $a$ and uniformly accelerated with acceleration $A$. This equation can be separated into its radial and angular parts. The behavior of the radial functions near the horizons is studied and used to examine the influence of $A$ on the phenomenon...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1408.4593

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5.0

Jun 30, 2018
06/18

by
B. Malekolkalami; K. Atazadeh; B. Vakili

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We investigate the effects of noncommutativity between the position-position, position-momentum and momentum-momentum of a phase space corresponding to a modified cosmological model. We show that the existence of such noncommutativity results in a Moyal Poisson algebra between the phase space variables in which the product law between the functions is of the kind of an $\alpha$-deformed product. We then transform the variables in such a way that the Poisson brackets between the dynamical...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1411.3623

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6.0

Jun 30, 2018
06/18

by
M. Abdel-Megied; Ragab M. Gad; E. A. Hegazy

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We have investigated an inhomogeneous Bianchi type-I cosmological model with electromagnetic field based on Lyra geometry. A new class of exact solutions have been obtained by considering the potentials of metric and displacement field are functions of coordinates t and x. The physical behavior of the obtained model is discussed.

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1411.5978

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5.0

Jun 30, 2018
06/18

by
Kun Meng; Da-Bao Yang; Zhan-Ning Hu

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A new four-dimensional black hole solution of Einstein-Born-Infeld-Yang-Mills theory is constructed, several degenerated forms of the black hole solution are presented. The related thermodynamical quantities are calculated, with which the first law of thermodynamics is checked to be satisfied. Identifying the cosmological constant as pressure of the system, the phase transition behaviors of the black hole in the extended phase space are studied.

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1701.06837

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Jun 30, 2018
06/18

by
Renato Vieira dos Santos; José A. C. Nogales

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We give a Lagrangian formulation for the theory of Rastall of gravitation. After proposing a Lagrangian density that reproduces the equations of motion postulated by Rastall, we study the cosmological consequences and fit the parameters using recent data from Hubble function $H(z).$ According to two model selection criteria, one based on corrected Akaike Information Criterion (AICc) and another on Bayesian Information Criterion (BIC), known to penalize models with a greater number of...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1701.08203

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6.0

Jun 30, 2018
06/18

by
Magd E. Kahil

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The problem of spinning and spin deviation equations for particles as defined by their microscopic effect has led many authors to revisit non-Riemannian geometry for being described torsion and its relation with the spin of elementary particles. We obtain a new method to detect the existence of torsion by deriving the equations of spin deviations in different classes of non-Riemannian geometries, using a modified Bazanski method. We find that translational gauge potentials and rotational gauge...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1701.04136

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11

Jun 30, 2018
06/18

by
Dimitris Moustos

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The analogy between the laws of black hole mechanics and the laws of thermodynamics led Bekenstein and Hawking to argue that black holes should be considered as real thermodynamic systems that are characterised by entropy and temperature. Black hole thermodynamics indicates a deeper connection between thermodynamics and gravity. We review and examine in detail the arguments that suggest an interpretation of gravity itself as a thermodynamic theory.

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1701.08967

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9.0

Jun 30, 2018
06/18

by
Jie-Xiong Mo; Feng Liang; Gu-Qiang Li

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We define a kind of heat engine via three-dimensional charged BTZ black holes. This case is quite subtle and needs to be more careful. The heat flow along the isochores does not equal to zero since the specific heat $C_V\neq0$ and this point completely differs from the cases discussed before whose isochores and adiabats are identical. So one cannot simply apply the paradigm in the former literatures. However, if one introduces a new thermodynamic parameter associated with the renormalization...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1701.00883

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6.0

Jun 30, 2018
06/18

by
J. Socorro; Omar E. Núñez

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The Multi-scalar field cosmology of the anisotropic Bianchi type I model is used in order to construct a family of potentials that are the best suited to model the inflation phenomenon. We employ the quantum potential approach to quantum mechanics due to Bohm in order to solve the corresponding Wheeler-DeWitt equation; which in turn enables us to restrict sensibly the aforementioned family of potentials. Supersymmetric Quantum Mechanics (SUSYQM) is also employed in order to constrain the...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1702.00478

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Jun 30, 2018
06/18

by
P. K. Agrawal; D. D. Pawar

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In the present paper an attempt has been made to study the spatially homogeneous and isotropic FRW model and axially symmetric spacetime in f(R) theory of gravity. We have obtained the solutions of the field equations in vacuum. To find the solutions of axially symmetric space-time we have assumed the relation between scale factor and scalar field and also we considered that scalar expansion ({\theta}) in the model is proportional to shear scalar ({\sigma}). The physical behavior for both...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1703.06258

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6.0

Jun 30, 2018
06/18

by
Ramon Lapiedra; Juan Antonio Morales-Lladosa

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A physically plausible Lema{\^{\i}}tre-Tolman-Bondi collapse in the marginally bound case is considered. By "physically plausible" we mean that the corresponding metric is ${\cal C}^1$ matched at the collapsing star surface and further that its {\em intrinsic} energy is, as due, stationary and finite. It is proved for this Lema{\^{\i}}tre-Tolman-Bondi collapse, for some parameter values, that its intrinsic central singularity is globally naked, thus violating the cosmic censorship...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1703.09133

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Jun 30, 2018
06/18

by
Jerónimo Cortez; William Cuervo; Hugo A. Morales-Técotl; Juan C. Ruelas

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The success of loop quantum cosmology to resolve classical singularities of homogeneous models has led to its application to the classical Schwarszchild black hole interior, which takes the form of a homogeneous Kantowski-Sachs model. The first steps of this were done in pure quantum mechanical terms, hinting at the traversable character of the would-be classical singularity, and then others were performed using effective heuristic models capturing quantum effects that allowed a geometrical...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1704.03362

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7.0

Jun 30, 2018
06/18

by
G. C. Samanta; Mayank Goel; R. Myrzakulov

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In this paper an explicit cosmological model which allows cosmological singularities are discussed. The generalized power-law and asymptotic expansions of the baro-tropic fluid index $\omega$ and equivalently the deceleration parameter $q$, in terms of cosmic time $'t'$ are considered. Finally, the strength of the found singularities is discussed.

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1703.00239

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6.0

Jun 30, 2018
06/18

by
Giorgio Papini

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In the study of covariant wave equations, linear gravity manifests itself through the metric deviation $\gamma_{\mu\nu}$ and a two-point vector potential $K_{\lambda}$ itself constructed from $\gamma_{\mu\nu}$ and its derivatives. The simultaneous presence of the two gravitational potentials is non contradictory. Particles also assume the character of quasiparticles and $K_{\lambda}$ carries information about the matter with which it interacts. We consider the influence of $K_{\lambda}$ on the...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1704.08163

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5.0

Jun 30, 2018
06/18

by
Donato Bini; Fernando de Felice; Andrea Geralico

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We study the behaviour of an initially spherical bunch of accelerated particles emitted along trajectories parallel to the symmetry axis of a rotating black hole. We find that, under suitable conditions, curvature and inertial strains compete to model the shape of axial outflows of matter contributing to generate jet-like structures. This is of course a purely kinematical effect which does not account by itself for physical processes underlying the formation of jets. In our analysis a crucial...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1408.4592

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6.0

Jun 30, 2018
06/18

by
Sumanta Chakraborty; T. Padmanabhan

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In the case of general relativity one can interpret the Noether charge in any bulk region as the heat content $TS$ of its boundary surface. Further, the time evolution of spacetime metric in Einstein's theory arises due to the difference $(N_{sur}-N_{bulk})$ of suitably defined surface and bulk degrees of freedom. We show that this thermodynamic interpretation generalizes in a natural fashion to all Lanczos-Lovelock models of gravity. The Noether charge, related to time evolution vector field,...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1408.4679

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10.0

Jun 30, 2018
06/18

by
Donato Bini; Andrea Geralico

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The dynamics of extended bodies endowed with multipolar structure up to the mass quadrupole moment is investigated in the Schwarzschild background according to the Dixon's model, extending previous works. The whole set of evolution equations is numerically integrated under the simplifying assumptions of constant frame components of the quadrupole tensor and that the motion of the center of mass be confined on the equatorial plane, the spin vector being orthogonal to it. The equations of motion...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1408.5261

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6.0

Jun 30, 2018
06/18

by
Luís C. B. Crispino; Sam R. Dolan; Atsushi Higuchi; Ednilton S. de Oliveira

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We compute the scattering cross section of Reissner-Nordstr\"om black holes for the case of an incident electromagnetic wave. We describe how scattering is affected by both the conversion of electromagnetic to gravitational radiation, and the parity-dependence of phase shifts induced by the black hole charge. The latter effect creates a helicity-reversed scattering amplitude that is non-zero in the backward direction. We show that from the character of the electromagnetic wave scattered in...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1409.4803

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5.0

Jun 30, 2018
06/18

by
Robert H. Cole; Jonathan R. Gair

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Likelihood surfaces in the parameter space of gravitational wave signals can contain many secondary maxima, which can prevent search algorithms from finding the global peak and correctly mapping the distribution. Traditional schemes to mitigate this problem maintain the number of secondary maxima and thus retain the possibility that the global maximum will remain undiscovered. By contrast, the recently proposed technique of likelihood transform can modify the structure of the likelihood surface...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1410.0597

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7.0

Jun 30, 2018
06/18

by
Ja. V. Balitsky; V. V. Kiselev

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The exact symmetry induced by the global shift of energy scale for the cosmological constant in the action of matter fields is spontaneously broken by setting the density of real vacuum energy and explicitly broken by the gravity that means the existence of Nambu--Goldstone boson, which transforms into the pseudo-Goldstone boson due to the gravity. We identify this boson with the inflaton in the Einstein frame of action for the fields, while the breaking is induced by a non-minimal interaction...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1410.2528

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4.0

Jun 30, 2018
06/18

by
Karl Wette

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All-sky, broadband, coherent searches for gravitational-wave pulsars are restricted by limited computational resources. Minimizing the number of templates required to cover the search parameter space, of sky position and frequency evolution, is one important way to reduce the computational cost of a search. We demonstrate a practical algorithm which, for the first time, achieves template placement with a minimal number of templates for an all-sky search, using the reduced supersky...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1410.6882

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4.0

Jun 30, 2018
06/18

by
Reinaldo J. Gleiser

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In this paper we study axial gravitational perturbations of an infinite static line source, represented by a form of the Levi-Civita metric. The perturbations are restricted to axial symmetry but break the cylindrical symmetry of the background metric. We analyze the gauge issues that arise in setting up the appropriate form of the perturbed metric and show that it is possible to restrict to diagonal terms, but that this does not fix the gauge completely. We derive the perturbation equations...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1408.0766

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7.0

Jun 30, 2018
06/18

by
Alex Vañó-Viñuales; Sascha Husa

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We consider unconstrained evolution schemes for the hyperboloidal initial value problem in numerical relativity as a promising candidate for the optimally efficient numerical treatment of radiating compact objects. Here, spherical symmetry already poses nontrivial problems and constitutes an important first step to regularize the resulting singular PDEs. We evolve the Einstein equations in their generalized BSSN and Z4 formulations coupled to a massless self-gravitating scalar field. Stable...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1412.4801

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7.0

Jun 30, 2018
06/18

by
Sven Zschocke

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The linearized field equations of general relativity in harmonic coordinates are given by an inhomogeneous wave equation. In the region exterior to the matter field, the retarded solution of this wave equation can be expanded in terms of 10 Cartesian symmetric and tracefree (STF) multipoles in post-Minkowskian approximation. For such a multipole decomposition only three and rather weak assumptions are required: 1. No-incoming radiation condition. 2. The matter source is spatially compact. 3. A...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1401.1056

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10.0

Jun 30, 2018
06/18

by
Clifford E Chafin

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Through an illuminating thought experiment we demonstrate that the nonsingular "continued collapse" picture of a black hole is the only consistent and physical one. We provide a class exact solutions on the boundary of the space of physical configurations. This will show that all the other known exact solutions are unphysical near the surface of the event horizon or in the interior. This will have important consequences for the no-hair conjecture and the kinds of persistent fields...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1402.1524

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Jun 28, 2018
06/18

by
R. Parthasarathy

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A 5-dimensional gravity theory, motivated by the brane world picture, with factorisable metric and with Kaluza scalar $G_{55}(r)$, is shown to give rise to a positive contribution to the Raychaudhuri equation. This inhibits the focusing of geodesics and possibly cause non-focusing of the geodesics. This feature is translated into the situation in which the universe has an infinite age and hence no beginning avoiding the big bang singularity.

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1507.01689

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Jun 28, 2018
06/18

by
Julian Barbour; Tim Koslowski; Flavio Mercati

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The universal validity of the second law of thermodynamics is widely attributed to a finely tuned initial condition of the universe. This creates a problem: why is the universe atypical? We suggest that the problem is an artefact created by inappropriate transfer of the traditional concept of entropy to the whole universe. Use of what we call the relational $N$-body problem as a model indicates the need to employ two distinct entropy-type concepts to describe the universe. One, which we call...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1507.06498

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7.0

Jun 28, 2018
06/18

by
Hellmut Baumgärtel

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It is well-known that there are four distinct basic types (two Big Bang types, Lemaitre and Big Crunch type) for solutions of the general Friedmann equation with positive cosmological constant, where radiation and matter do not couple (see e.g. [2, p.7]. In that paper the system of case distinction parameters contains a "critical radiation parameter" $\sigma_{cr}$. The present note contains the constructive description of the so-called {\em border lines} between Big Bang/Big Crunch...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1511.02620

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6.0

Jun 28, 2018
06/18

by
M. Sharif; Saadia Mumtaz

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In this paper, we study the dynamical instability of gaseous sphere under radial oscillations approaching the Reissner-Nordstr\"om limit. For this purpose, we derive linearized perturbed equation of motion following the Eulerian and Lagrangian approaches. We formulate perturbed pressure in terms of adiabatic index by employing the conservation of baryon numbers. A variational principle is established to evaluate characteristic frequencies of oscillations which lead to the criteria for...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1512.03098

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Jun 26, 2018
06/18

by
Mitchell Revalski; Will Rhodes; Thulsi Wickramasinghe

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We provide calculations and theoretical arguments supporting the emission of electromagnetic radiation from charged particles accelerated by gravitational waves (GWs). These waves have significant indirect evidence to support their existence, yet they interact weakly with ordinary matter. We show that the induced oscillations of charged particles interacting with a GW, which lead to the emission of electromagnetic radiation, will also result in wave attenuation. These ideas are supported by a...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1502.00893

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Jun 27, 2018
06/18

by
Katy Clough; Pau Figueras; Hal Finkel; Markus Kunesch; Eugene A. Lim; Saran Tunyasuvunakool

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In this work, we introduce GRChombo: a new numerical relativity code which incorporates full adaptive mesh refinement (AMR) using block structured Berger-Rigoutsos grid generation. The code supports non-trivial "many-boxes-in-many-boxes" mesh hierarchies and massive parallelism through the Message Passing Interface (MPI). GRChombo evolves the Einstein equation using the standard BSSN formalism, with an option to turn on CCZ4 constraint damping if required. The AMR capability permits...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1503.03436

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Jun 27, 2018
06/18

by
Laura Castelló Gomar; Mercedes Martín-Benito; Guillermo A. Mena Marugán

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We consider cosmological perturbations around homogeneous and isotropic spacetimes minimally coupled to a scalar field and present a formulation which is designed to preserve covariance. We truncate the action at quadratic perturbative order and particularize our analysis to flat compact spatial sections and a field potential given by a mass term, although the formalism can be extended to other topologies and potentials. The perturbations are described in terms of Mukhanov-Sasaki gauge...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1503.03907

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Jun 27, 2018
06/18

by
Dennis Philipp; Volker Perlick

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In a previous paper we have considered the Regge-Wheeler equation for fields of spin $s=0$, $1$ or $2$ on the Schwarzschild spacetime in coordinates that are regular at the horizon. In particular, we have constructed in Eddington-Finkelstein coordinates exact solutions in terms of series that are regular at the horizon and converge on the entire open domain from the central singularity to infinity. Here we extend this earlier work in two different directions. Firstly, we consider in...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1503.08361

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Jun 27, 2018
06/18

by
Yu Chen; Edward Teo

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We present a new five-parameter class of Ricci-flat solutions in four dimensions with Euclidean signature. The solution is asymptotically locally flat (ALF), and contains a finite asymptotic NUT charge. When this charge is sent to infinity, the solution becomes asymptotically locally Euclidean (ALE), and one in fact obtains the Ricci-flat Plebanski-Demianski solution. The solution we have found can thus be regarded as an ALF generalisation of the latter solution. We also show that it can be...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1504.01235

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Jun 27, 2018
06/18

by
Z. Haba

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We discuss tensor metric perturbations in a magnetic field around the homogeneous Juttner equilibrium of massless particles in an expanding universe. We solve the Liouville equation and derive the energy-momentum tensor up to linear terms in the metric and in the magnetic field.The term linear in the magnetic field is different from zero if the total charge of the primordial plasma is non-zero. We obtain an analytic formula for temperature fluctuations treating the tensor metric perturbations...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1504.03709

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7.0

Jun 29, 2018
06/18

by
Nahomi Kan; Kiyoshi Shiraishi

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In this paper, we study rotating boson stars in the large coupling limit as well as in the Newtonian limit. We investigate the equilibrium solutions in four and five dimensions by adopting some analytical approximations. We show that the relations among the radius, angular momentum, Newtonian energy and quadrupole moment (for the four-dimensional solution) of the boson star can be qualitatively realized for the minimal number of boson star parameters.

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1605.02846

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Jun 29, 2018
06/18

by
Chikun Ding; Changqing Liu

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In Einstein-aether theory, violating Lorentz invariance permits some super-luminal communications, and the universal horizon can trap excitations traveling at arbitrarily high velocities. To better understand the nature of these universal horizons, we first modify the ray tracing method, and then use it to study their surface gravity in charged Einstein-aether black hole spacetime. Instead of the previous result in Ref. [Phys. Rev. D 89, 064061], our results show that the surface gravity of the...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1611.03153

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Jun 30, 2018
06/18

by
Joan Josep Ferrando; Juan Antonio Sáez

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We complete the intrinsic characterization of spherically symmetric solutions partially accomplished in a previous paper [Class.Quant.Grav. (2010) 27 205024]. In this approach we consider every compatible algebraic type of the Ricci tensor, and we analyze specifically the conformally flat case for perfect fluid and Einstein-Maxwell solutions. As a direct application we obtain the {\em ideal} labeling (exclusively involving explicit concomitants of the metric tensor) of the Schwarzschild...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1701.05023

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3.0

Jun 30, 2018
06/18

by
Nora Bretón; C. E. Ramírez-Codiz

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The stationary axisymmetric spacetime coupled to nonlinear Born-Infeld electrodynamics is studied. The solution was derived by Plebanski et al (1984) and it is characterized by six free parameters: mass, NUT charge, electric and magnetic charge, Born-Infeld parameter and cosmological constant. The geodesic and Lorentz force equations are integrated, and a qualitative analysis of the effect of varying the parameters in the effective potential is provided. Then the light and charged particle...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1408.4376

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Jun 30, 2018
06/18

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Christopher J. Moore; Jonathan R. Gair

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Posterior distributions on parameters computed from experimental data using Bayesian techniques are only as accurate as the models used to construct them. In many applications these models are incomplete, which both reduces the prospects of detection and leads to a systematic error in the parameter estimates. In the analysis of data from gravitational wave detectors, for example, accurate waveform templates can be computed using numerical methods, but the prohibitive cost of these simulations...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1412.3657

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Jun 30, 2018
06/18

by
Alfredo Iorio

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The case for a dedicated laboratory, to test hep-th models on analogue systems, is briefly made. The focus is on graphene.

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1412.5160

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Jun 30, 2018
06/18

by
Nistor Nicolaevici

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We consider the excitation of a finite-length inertial Unruh detector in the Minkowski vacuum with an adiabatic switch on of the interaction in the infinite past and a sudden switch off at finite times, and obtain the excitation probability via a numerical calculation using the expansion of the quantum field in spherical modes. We evaluate first the excitation probabilities for the final states of the field with one particle per mode, and then we sum over the modes. An interesting feature is...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1704.03708

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Jun 30, 2018
06/18

by
Paul Tod

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We take a step towards characterising stationary data for the vacuum Einstein equations, by finding a necessary condition on initial data for which the evolution is a solution of the vacuum equations admitting a Killing vector, which is time-like at least in some region of the Cauchy development.

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1702.00324

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Jun 30, 2018
06/18

by
Nupur Paul; S. S. De; Farook Rahaman

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We consider a very general scenario of our universe where its geometry is characterized by the Finslerian structure on the underlying spacetime manifold, a generalization of the Riemannian geometry. Now considering a general energy-momentum tensor for matter sector, we derive the gravitational field equations in such spacetime. Further, to depict the cosmological dynamics in such spacetime proposing an interesting equation of state identified by a sole parameter $\gamma$ which for isotropic...

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1704.03339

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Jun 30, 2018
06/18

by
Lorenzo Fatibene; Simon Garruto; Maurizio Polistina

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We review the definition by Perlick of standard clocks in a Weyl geometry and show how a congruence of clocks can be used to fix the conformal gauge in the EPS framework. Examples are discussed in details.

Topic: General Relativity and Quantum Cosmology

Source: http://arxiv.org/abs/1410.1284