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Cosmological observatories Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-18 Dionysios Anninos, Damián A Galante and Chawakorn Maneerat
We study the static patch of de Sitter space in the presence of a timelike boundary. We impose that the conformal class of the induced metric and the trace of the extrinsic curvature, K, are fixed at the boundary. We present the thermodynamic structure of de Sitter space subject to these boundary conditions, for static and spherically symmetric configurations to leading order in the semiclassical approximation
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Quantum group intertwiner space from quantum curved tetrahedron Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-18 Muxin Han, Chen-Hung Hsiao and Qiaoyin Pan
In this paper, we develop a quantum theory of homogeneously curved tetrahedron geometry, by applying the combinatorial quantization to the phase space of tetrahedron shapes defined in Haggard et al (2016 Ann. Henri Poincaré 17 2001–48). Our method is based on the relation between this phase space and the moduli space of SU(2) flat connections on a 4-punctured sphere. The quantization results in the
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Particle and light motion in Lyra–Schwarzschild spacetime Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-17 R R Cuzinatto, E M de Morais and B M Pimentel
In this paper we recall the static and spherically symmetric solution derived within LyST gravity. LyST stands for ‘Lyra Scalar-Tensor’ and is a scalar-tensor proposal for the gravitational interaction modifying general relativity by adopting Lyra manifold as the spacetime substrate. Lyra manifold is characterized both by the metric tensor and the scale ; the latter being an integral part of the definition
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Holographic vacuum energy regularization and corrected entropy of de Sitter space Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-17 S Jalalzadeh, H Moradpour and H Tebyanian
We propose that the spectrum of the surface area of the apparent horizon (AH) of de Sitter (dS) spacetime leads to corrected temperature and entropy of the dS spacetime, offering new insights into its thermodynamic properties. This is done by employing the spectrum of the AH radius, acquired from the Wheeler–DeWitt (WDW) equation, together with the Stefan–Boltzmann law, the time-energy uncertainty
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Spherical symmetric solutions of conformal Killing gravity: black holes, wormholes, and sourceless cosmologies Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-17 Gérard Clément and Khireddine Nouicer
The most general set of static and spherically symmetric solutions for conformal Killing gravity coupled to Maxwell fields is presented in closed form. These solutions, depending on six parameters, include non-asymptotically flat black holes or naked singularities, non-asymptotically flat traversable wormholes, and (possibly singularity-free) closed universes. We also consider the inverse problem,
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Cramér-Rao lower bounds on parameter estimation for a circular binary of supermassive black holes in gravitational wave observations using pulsar timing array Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-16 Qing-Qing Duan, Jin Liu and Zhi-Wei Kang
Pulsar timing arrays (PTAs) are effective in detecting low-frequency gravitational waves (GWs), especially in circular binary systems of supermassive black holes. To evaluate the effectiveness and accuracy of PTAs in searching for GW parameter estimation, we use the Cramer-Rao lower bound to estimate the parameters of the Virgo source under various search conditions, including both evolving and non-evolving
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Pseudo-supersymmetric approach to the Dirac operator in the Schwarzschild spacetime Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-15 Özlem Yeşiltaş
We have discussed the Dirac equation in Schwarzschild spacetime using pseudo-supersymmetric quantum mechanics and have obtained the partner Hamiltonian of the initial Hamiltonian operator. We demonstrate that the partner metric tensors, corresponding to these Hamiltonians, can be derived using the intertwining relations inherent in pseudo-supersymmetric approaches. We have seen that the Schwarzschild
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Reconstructing the metric in group field theory Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-15 Steffen Gielen and Lisa Mickel
We study a group field theory (GFT) for quantum gravity coupled to four massless scalar fields, using these matter fields to define a (relational) coordinate system. We exploit symmetries of the GFT action, in particular under shifts in the values of the scalar fields, to derive a set of classically conserved currents, and show that the same conservation laws hold exactly at the quantum level regardless
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Constraints on extra dimensions theories from gravitational quantum barrier experiments Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-15 J M Rocha and F Dahia
We discuss the quantum-bouncer experiment involving ultracold neutrons in a braneworld scenario. Extra-dimensional theories typically predict the strengthening of gravitational interactions over short distances. In this paper, we specifically study the anomalous gravitational interaction between the bouncing neutron and the reflecting mirror, resulting from hidden dimensions, and investigate the effects
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Metrizability of SO(3) -invariant connections: Riemann versus Finsler Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-10 N Voicu and S G Elgendi
For a torsion-free affine connection on a given manifold, which does not necessarily arise as the Levi–Civita connection of any pseudo-Riemannian metric, it is still possible that it corresponds in a canonical way to a Finsler structure; this property is known as Finsler (or Berwald–Finsler) metrizability. In the present paper, we clarify, for four-dimensional SO(3)-invariant, Berwald–Finsler metrizable
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Note on black holes with kilometer-scale ultraviolet regulators Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-10 Jens Boos and Christopher D Carone
Regular black hole metrics involve a universal, mass-independent regulator that can be up to while remaining consistent with terrestrial tests of Newtonian gravity and astrophysical tests of general relativistic orbits. However, for such large values of the regulator scale, the metric describes a compact, astrophysical-mass object with no horizon rather than a black hole. We note that allowing the
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Hexadecapole at the heart of nonlinear electromagnetic fields Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-09 Ana Bokulić, Tajron Jurić and Ivica Smolić
In classical Maxwell’s electromagnetism, the monopole term of the electric field is proportional to r−2, while higher order multipole terms, sourced by anisotropic sources, fall-off faster. However, in nonlinear electromagnetism even a spherically symmetric field has multipole-like contributions. We prove that the leading subdominant term of the electric field, defined by nonlinear electromagnetic
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Metric perturbations of Kerr spacetime in Lorenz gauge: circular equatorial orbits Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-09 Sam R Dolan, Leanne Durkan, Chris Kavanagh, Barry Wardell
We construct the metric perturbation in Lorenz gauge for a compact body on a circular equatorial orbit of a rotating black hole (Kerr) spacetime, using a newly-developed method of separation of variables. The metric perturbation is formed from a linear sum of differential operators acting on Teukolsky mode functions, and certain auxiliary scalars, which are solutions to ordinary differential equations
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Induced motions on Carroll geometries Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-09 L Marsot
In this article, we consider some Carrollian dynamical systems as effective models on null hypersurfaces in a Lorentzian spacetime. We show that we can realize Carroll models from more usual ‘relativistic’ theories. In particular, we show how ambient null geodesics imply the classical ʼno Carroll motion’ and, more interestingly, we find that the ambient model of chiral fermions implies Hall motion on
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Can a radiation gauge be horizon-locking? Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-08 Leo C Stein
In this short Note, I answer the titular question: yes, a radiation gauge can be horizon-locking. Radiation gauges are very common in black hole perturbation theory. It’s also very convenient if a gauge choice is horizon-locking, i.e. the location of the horizon is not moved by a linear metric perturbation. Therefore it is doubly convenient that a radiation gauge can be horizon-locking, when some simple
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Neutrinos as possible probes for quantum gravity Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-08 M D C Torri, L Miramonti
In this paper, we aim to explore the interplay between neutrinos and quantum gravity, illustrating some proposals about the use of these particles as probes for the supposed quantized structure of spacetime. The residual signatures of a more fundamental theory of quantum gravity can manifest themselves modifying the free particle dispersion relations and the connected velocity. In neutrino sector these
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Moving mirrors and event horizons in non-flat background geometry Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-08 Evgenii Ievlev
Moving mirrors have been used for a long time as simple models for studying various properties of black hole radiation, such as the thermal spectrum and entanglement entropy. These models are typically constructed to mimic the collapse of a spherically symmetric distribution of matter in the Minkowski background. We generalize this correspondence to the case of non-trivial background geometry and consider
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A topological drive for spacetime travel Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-08 Tingqi Cai, Yi Wang
We present a toy metric of spacetime travel from topological change. A bubble-like baby Universe is detached and re-attached from our Universe. Depending on where the bubble is re-attached, matter may travel superluminally or backwards-in-time through the bubble. Quasiregular singularities are formed at the detachment and re-attachment spacetime points. The spacetime is traversable and not covered
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Spherically symmetric electrovac spacetimes in conformal Killing gravity Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-05 Alan Barnes
Recently Harada proposed a third-order gravitational theory for the derivatives of the metric. Mantica and Molinari showed that Harada’s theory may be recast into the form of Einstein’s field equations (EFEs) with an additional source term which is a second-order conformal Killing tensor. Accordingly they named the theory conformal Killing gravity. However, they overlooked the fact that all solutions
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Quadrupolar radiation in de Sitter: displacement memory and Bondi metric Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-04 Geoffrey Compère, Sk Jahanur Hoque, Emine Şeyma Kutluk
We obtain the closed form expression for the metric perturbation around de Sitter spacetime generated by a matter source below Hubble scale both in generalized harmonic gauge and in Bondi gauge up to quadrupolar order in the multipolar expansion, including both parities (i.e. both mass and current quadrupoles). We demonstrate that such a source causes a displacement memory effect close to future infinity
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Visualisation of counter-rotating dust disks using ray tracing methods Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-04 Eddy B de Leon, Jörg Frauendiener, Christian Klein
Physical aspects of stationary axisymmetric vacuum spacetimes given by exact solutions of the Einstein equations are discussed via ray tracing. A detailed study of the spacetime generated by a disk of counter-rotating dust is presented. The spacetime is given in explicit form in terms of hyperelliptic theta functions. The numerical approach to ray tracing is set up for general stationary axisymmetric
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Comparative analysis of dark energy compact stars in f(T,T) and f(T) gravity theories via conformally flat condition Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-03 Allah Ditta, G Mustafa, S K Maurya, Değer Sofuoğlu, Asif Mahmood
This manuscript is the first investigation of dark energy celestial phenomena in the modified gravity theory by examining dark energy compact stars within the context of modified f(T,T) gravity. In order to compare the outcomes of the f(T,T) and f(T) gravity theories, the model f(T,T)=αT(r)+βT(r)+ϕ is selected. This model is then simplified to f(T) gravity by setting β = 0. The f(T) gravity is torsion-based
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The interface of gravity and dark energy Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-01 Kristen Lackeos, Richard Lieu
At sufficiently large radii dark energy modifies the behavior of (a) bound orbits around a galaxy and (b) virialized gas in a cluster of galaxies. Dark energy also provides a natural cutoff to a cluster’s dark matter halo. In (a) there exists a maximum circular orbit beyond which periodic motion is no longer possible, and orbital evolution near critical binding is analytically calculable using an adiabatic
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Generalized second law for non-minimally coupled matter theories Classical Quant. Grav. (IF 3.6) Pub Date : 2024-07-01 Prateksh Dhivakar, Krishna Jalan
We establish the generalized second law (GSL) within the framework of higher curvature gravity theories, considering non-minimal couplings in the matter sector. Our proof pertains to the regime of linearized fluctuations around equilibrium black holes, aligning with previous works by Wall and Sarkar. Notably, while prior proofs addressed various gravity theories such as Lovelock theory and higher curvature
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Gravity with torsion as deformed BF theory * Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-28 Alberto S Cattaneo, Leon Menger, Michele Schiavina
We study a family of (possibly non topological) deformations of BF theory for the Lie algebra obtained by quadratic extension of so(3,1) by an orthogonal module. The resulting theory, called quadratically extended General Relativity (qeGR), is shown to be classically equivalent to certain models of gravity with dynamical torsion. The classical equivalence is shown to promote to a stronger notion of
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Discovering Love numbers through resonance excitation during extreme mass ratio inspirals Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-26 Shani Avitan, Ram Brustein, Yotam Sherf
General Relativity predicts that black holes (BHs) do not possess an internal structure and consequently cannot be excited. This leads to a specific prediction about the waveform of gravitational waves (GWs) which they emit during a binary BH inspiral and to the vanishing of their Love numbers. However, if astrophysical BHs do possess an internal structure, their Love numbers would no longer vanish
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Quasinormal modes of charged BTZ black holes Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-26 R D B Fontana
We investigate the scalar field equation in a (2+1) -dimensional charged BTZ black hole. The quasinormal spectra of the solution are obtained applying two different methods and good convergence between both is achieved. Using the characteristic integration technique we tested the geometry evidencing its stability against linear scalar perturbations. As a consequence a two pattern set of frequencies
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Kodama-like vector fields in axisymmetric spacetimes Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-25 Philipp Dorau, Rainer Verch
We extend the concept of the Kodama symmetry, a quasi-local time translation symmetry for dynamical spherically symmetric spacetimes, to a specific class of dynamical axisymmetric spacetimes, namely the families of Kerr–Vaidya and Kerr–Vaidya–de Sitter spacetimes. We study some geometrical properties of the asymptotically flat Kerr–Vaidya metric, such as the Brown–York mass and the Einstein tensor
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Towards a realistic dipole cosmology: the dipole ΛCDM model Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-25 Ehsan Ebrahimian, Chethan Krishnan, Ranjini Mondol, M M Sheikh-Jabbari
Dipole cosmology is the maximally Copernican generalization of the FLRW paradigm that can incorporate bulk flows in the cosmic fluid. In this paper, we first discuss how multiple fluid components with independent flows can be realized in this set up. This is the necessary step to promote ‘tilted’ Bianchi cosmologies to a viable framework for cosmological model building involving fluid mixtures (as
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Do black holes remember what they are made of? Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-25 Harshraj Bandyopadhyay, David Radice, Aviral Prakash, Arnab Dhani, Domenico Logoteta, Albino Perego, Rahul Kashyap
We study the ringdown signal of black holes formed in prompt-collapse binary neutron star mergers. We analyze data from 47 numerical relativity simulations. We show that the (ℓ=2,m=2) and (ℓ=2,m=1) multipoles of the gravitational wave signal are well fitted by decaying damped exponentials, as predicted by black-hole perturbation theory. We show that the ratio of the amplitude in the two modes depends
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Superspace worldline formalism approach to quantum gravity: dimensional reduction and holography Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-25 J-B Roux
Using the ADM formalism, we demonstrate that the Hamiltonian formulation of Quantum Gravity is exactly in the form of a worldline formalism in the superspace. We then show that the Keldysh partition function reduces to the partition function of Euclidean 3D gravity. After discussing the meaning of the time parameter, we show that in the gauge fields formalism, our Keldysh partition function reduces
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The Einstein–Hilbert action for entropically dominant causal sets Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-24 Peter Carlip, Steve Carlip, Sumati Surya
In the path integral formulation of causal set quantum gravity, the quantum partition function is a phase-weighted sum over locally finite partially ordered sets, which are viewed as discrete quantum spacetimes. It is known, however, that the number of ‘layered’ sets—a class of causal sets that look nothing like spacetime manifolds—grows superexponentially with the cardinality n, giving an entropic
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On the evolution of the volume in Loop Quantum Cosmology Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-24 Beatriz Elizaga Navascués
The dynamics of the expectation value of the volume is one of the key ingredients behind the replacement of the Big Bang singularity by a bounce in Loop Quantum Cosmology. As such, it is of great importance that this quantity is mathematically well-defined in the space of physical states of the theory. A number of caveats have been raised about such a definition entering in conflict with the quantum
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Automated evaluation of environmental coupling for Advanced LIGO gravitational wave detections Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-20 A F Helmling-Cornell, P Nguyen, R M S Schofield, R Frey
The extreme sensitivity required for direct observation of gravitational waves by the Advanced LIGO detectors means that environmental noise is increasingly likely to contaminate Advanced LIGO gravitational wave signals if left unaddressed. Consequently, environmental monitoring efforts have been undertaken and novel noise mitigation techniques have been developed which have reduced environmental coupling
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High-frequency solutions to the Einstein equations Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-20 Cécile Huneau, Jonathan Luk
We review recent mathematical results concerning the high-frequency solutions to the Einstein vacuum equations and the limits of these solutions. In particular, we focus on two conjectures of Burnett, which attempt to give an exact characterization of high-frequency limits of vacuum spacetimes as solutions to the Einstein–massless Vlasov system. Some open problems and future directions are discussed
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Probing primordial black hole scenarios with terrestrial gravitational wave detectors Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-19 Guillem Domènech, Misao Sasaki
It is possible that primordial black holes (PBHs) constitute (or constituted) a significant fraction of the energy budget of our Universe. Terrestrial gravitational wave detectors offer the opportunity to test the existence of PBHs in two different mass ranges, from 102g−1016g to 10−6M⊙−100M⊙ . The first mass window is open via induced gravitational waves, and the second one is by gravitational waves
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Impact of energy–momentum conservation violation on the configuration of compact stars and their GW echoes Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-17 Jyatsnasree Bora, Dhruba Jyoti Gogoi, S K Maurya, Ghulam Mustafa
This work investigates the impacts of energy–momentum conservation violation on the configuration of strange stars constraint with gravitational wave (GW) event GW190814 as well as eight recent observations of compact objects. The GW echoes from these interesting classes of compact objects are also calculated. To describe the matter of strange stars, we have used two different equations of state (EoSs):
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Casimir wormholes in Brans–Dicke theory Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-14 Amir Hadi Ziaie, Mohammad Reza Mehdizadeh
In recent years there has been a growing interest in the field of wormhole physics in the presence of Casimir effect. As this effect provides negative energy density, it can be utilized as an ideal candidate for the exotic matter required for creating a traversable wormhole. In the context of modified theories of gravity such as Brans–Dicke (BD) theory (Brans and Dicke 1961 Phys. Rev. 124 925), wormhole
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Searches for compact binary coalescence events using neural networks in LIGO/Virgo third observation period Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-12 A Menéndez-Vázquez, M Andrés-Carcasona, M Martínez, Ll M Mir
We present the results on the search for the coalescence of compact binary mergers using convolutional neural networks (CNNs) and the LIGO/Virgo data for the O3 observation period. Two-dimensional images in time and frequency are used as input. The analysis is performed in three separate mass regions covering the range for the masses in the binary system from 0.2 M ⊙ to 100 M ⊙ , excluding very asymmetric
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The transformation of the rotational energy of a Kerr black hole Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-12 Shu-Rui Zhang, Mikalai Prakapenia
This paper analyzes the feedback of the rotational energy extraction from a Kerr black hole (BH) by the ‘ballistic method’, i.e. the test particle decay in the BH ergosphere pioneered by Roger Penrose. The focus is on the negative energy counterrotating particles (which can be massive or massless) going in towards the horizon, and the feedback on the BH irreducible mass is assessed. Generally, the
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Cosmological higher-curvature gravities Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-12 Javier Moreno, Ángel J Murcia
We examine higher-curvature gravities whose Friedmann–Lemaître–Robertson–Walker configurations are specified by equations of motion which are of second order in derivatives, just like in Einstein gravity. We name these theories Cosmological Gravities and initiate a systematic exploration in dimensions D⩾3 . First, we derive an instance of Cosmological Gravity to all curvature orders and dimensions
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Einstein-Gauss-Bonnet dark matter halo: negative masses, rotation curves and the origin of dark matter effects Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-10 Omar Chahboun, Rachid Ahl Laamara, El Hassan Saidi
This work presents a novel approach to address the longstanding challenge posed by the rotation curves of galaxies and the associated missing mass problem. Utilizing the four-dimensional modified gravity framework of Einstein-Gauss-Bonnet (EGB), we develop a new model that integrates the concept of dark matter featuring negative mass due to the Gauss-Bonnet term. Our methodology involves using the
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Modeling and reduction of high frequency scatter noise at LIGO Livingston Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-07 Siddharth Soni, Jane Glanzer, Anamaria Effler, Valera Frolov, Gabriela González, Arnaud Pele, Robert Schofield
The sensitivity of aLIGO detectors is adversely affected by the presence of noise caused by light scattering. Low frequency seismic disturbances can create higher frequency scattering noise adversely impacting the frequency band in which we detect gravitational waves. In this paper, we analyze instances of a type of scattered light noise we call ‘Fast Scatter’ that is produced by motion at frequencies
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Universality of quantum time dilation Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-07 Kacper Dębski, Piotr T Grochowski, Rafał Demkowicz-Dobrzański, Andrzej Dragan
Time dilation is a difference in measured time between two clocks that either move with different velocities or experience different gravitational potentials. Both of these effects stem from the theory of relativity and are usually associated with classically defined trajectories, characterized by position, momentum, and acceleration. However, when spatial degrees of freedom are treated in a quantum
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Gauge-invariant formulation for the gravitational wave equations Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-07 Junpei Harada
A gauge-invariant formulation for the gravitational wave equations is presented. Using this approach, weak, plane wave solutions in a vacuum are derived in various theories. These include general relativity with two modes of polarization with helicity ±2, Yang’s theory with three modes of polarization with helicity ±2 and 0, and so-called ‘general metric theories’ with six modes of polarization with
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Gravitational wave displacement and velocity memory effects Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-06 Lydia Bieri, Alexander Polnarev
In this article, we compare in detail the linear and nonlinear approach to the Gravitational Waves Displacement and Velocity Memory (GWDM and GWVM) effects. We consider astrophysical situations that give rise to gravitational waves with GWVM effect, i.e. with a residual velocity (the so-called ‘velocity-coded memory’) and discuss the possibility of future detection of the GWVM effect.
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Black hole interior quantization: a minimal uncertainty approach Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-06 Pasquale Bosso, Octavio Obregón, Saeed Rastgoo, Wilfredo Yupanqui
In a previous work we studied the interior of the Schwarzschild black hole implementing an effective minimal length, by applying a modification to the Poisson brackets of the theory. In this work we perform a proper quantization of such a system. Specifically, we quantize the interior of the Schwarzschild black hole in two ways: once by using the standard quantum theory, and once by following a minimal
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Future of Bianchi I magnetic cosmologies with kinetic matter Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-06 Ho Lee, Ernesto Nungesser
We show under the assumption of small data that solutions to the Einstein-Vlasov system with a pure magnetic field and Bianchi I symmetry isotropise and tend to dust solutions. We also obtain the decay rates for the main variables. This generalises part of the work (LeBlanc 1997 Class. Quantum Grav. 14 2281–301) concerning the future behaviour of orthogonal perfect fluids with a linear equation of
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Optimal shielding for Einstein gravity Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-06 Bruno Le Floch, Philippe G LeFloch
To construct asymptotically-Euclidean Einstein’s initial data sets, we introduce the localized seed-to-solution method, which projects from approximate to exact solutions of the Einstein constraints. The method enables us to glue together initial data sets in multiple asymptotically-conical regions, and in particular construct data sets that exhibit the gravity shielding phenomenon, specifically that
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Asymptotic symmetries of gravity in the gauge PDE approach Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-05 Maxim Grigoriev, Mikhail Markov
We propose a framework to study local gauge theories on manifolds with boundaries and their asymptotic symmetries, which is based on representing them as so-called gauge PDEs. These objects extend the conventional BV-AKSZ sigma-models to the case of not necessarily topological and diffeomorphism invariant systems and are known to behave well when restricted to submanifolds and boundaries. We introduce
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Deflection of light by a Reissner–Nordström black hole and Painlevé VI equation Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-05 Tadashi Sasaki
We consider the bending angle of the trajectory of a photon incident from and deflected to infinity around a Reissner–Nordström black hole. We treat the bending angle as a function of the squared reciprocal of the impact parameter and the squared electric charge of the background normalized by the mass of the black hole. It is shown that the bending angle satisfies a system of two inhomogeneous linear
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Membrane models as a means of propulsion in general relativity: super-luminal warp-drive that satisfies the weak energy condition Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-05 Greg Huey
Presented are toy-models for sub-luminal and super-luminal warp-drives in 3+1 dimensions. The models are constructed in a chimeric manner—as different bulk space-times separated by thin membranes. The membranes contain perfect-fluid-like stress-energy tensors. The Israel junction conditions relate this stress-energy to a jump in extrinsic curvature across the brane, which in turn manifests as apparent
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On the stability of Einsteinian cubic gravity black holes in EFT Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-05 Pablo Bueno, Pablo A Cano, Robie A Hennigar
In this note we revisit the analysis performed in De Felice and Tsujikawa (2023 Phys. Lett. B 843 138047) of odd-parity perturbations around static and spherically symmetric black holes in Einsteinian cubic gravity (ECG). We show that the additional propagating modes always have masses much above the cutoff of the theory. Therefore, contrary to what is claimed in that paper, the ECG black holes remain
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Preliminary sensitivity study for a gravitational redshift measurement with China’s Lunar exploration project Classical Quant. Grav. (IF 3.6) Pub Date : 2024-06-03 Cheng-Gang Qin, Tong Liu, Xiao-Yi Dai, Peng-Bin Guo, Weisheng Huang, Xiang-Pei Liu, Yu-Jie Tan, Cheng-Gang Shao
General relativity (GR) is a highly successful theory that describes gravity as a geometric phenomenon. The gravitational redshift, a classic test of GR, can potentially be violated in alternative gravity theories, and experimental tests on this effect are crucial for our understanding of gravity. In this paper, considering the space-ground clock comparisons with free-space links, we discuss a high-precision
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Geometric interpretation of Tensor-Vector-Scalar theory in a Kaluza–Klein reference fluid Classical Quant. Grav. (IF 3.6) Pub Date : 2024-05-31 Timothy D Andersen
Gravitational alternatives to dark matter require additional fields or assumptions beyond general relativity while continuing to agree with tight solar system constraints. Modified Newtonian Dynamics (MOND), for example, predicts the Tully–Fisher relation for galaxies more accurately than dark matter models while limiting to Newtonian gravity in the solar system. On the other hand, MOND does a poor
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ℓ -Proca stars Classical Quant. Grav. (IF 3.6) Pub Date : 2024-05-31 Claudio Lazarte, Miguel Alcubierre
Initially applied to the scalar case, we extend the applicability of the multi-field generalization with angular momentum of bosonic stars to the vector case, in order to obtain new configurations that generalize the one-field spherical Proca stars. These new objects, which we call ℓ -Proca stars, arise as stationary and spherically symmetric bosonic stars solutions of the Einstein-(multi)Proca system
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On the generalization of the Kruskal–Szekeres coordinates: a global conformal charting of the Reissner–Nordström spacetime Classical Quant. Grav. (IF 3.6) Pub Date : 2024-05-31 Fawzi Aly, Dejan Stojkovic
The Kruskal–Szekeres coordinate construction for the Schwarzschild spacetime could be interpreted simply as a squeezing of the t-line into a single point, at the event horizon r=2M . Starting from this perspective, we extend the Kruskal charting to spacetimes with two horizons, in particular the Reissner–Nordström manifold, MRN . We develop a new method to construct Kruskal-like coordinates through
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Necessity of quantizable geometry for quantum gravity Classical Quant. Grav. (IF 3.6) Pub Date : 2024-05-31 A K Mehta
In this paper, Dirac Quantization of 3D gravity in the first-order formalism is attempted where instead of quantizing the connection and triad fields, the connection and the triad 1-forms themselves are quantized. The exterior derivative operator on the space of differential forms is treated as the ‘time’ derivative to compute the momenta conjugate to these 1-forms. This manner of quantization allows
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Infinitely degenerate slowly rotating solutions in f(R) gravity Classical Quant. Grav. (IF 3.6) Pub Date : 2024-05-30 Alan Sunny, Semin Xavier, S Shankaranarayanan
This work tests the no-hair conjecture in f(R) gravity models. No-hair conjecture asserts that all black holes in general relativity coupled to any matter must be Kerr–Newman type. However, the conjecture fails in some cases with non-linear matter sources. Here, we address this by explicitly constructing multiple slow-rotating black hole solutions, up to second order in rotational parameter, for a
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Asymptotically safe cosmology with non-canonical scalar field Classical Quant. Grav. (IF 3.6) Pub Date : 2024-05-28 Rituparna Mandal, Soma Sanyal
We investigate the quantum modified cosmological dynamical equations in a Friedmann–Lemaître–Robertson–Walker universe filled with a barotropic fluid and a general non-canonical scalar field characterized by a Lagrangian similar to k-essence model but with a potential term. Quantum corrections are incorporated by considering the running of the gravitational and potential couplings, employing the functional