-
Spinor fields, CPTM symmetry and smallness of cosmological constant in framework of extended manifold Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-26 S Bondarenko, V De La Hoz-Coronell
A model of an extended manifold for the Dirac spinor field is considered. Two Lagrangians related by charge-parity-time-mass symmetry are constructed for a pair of the Dirac spinor fields with each spinor field defined in a separate manifold. An interaction between the matter fields in the manifolds is introduced through gravity. A fermionic effective action of the general system is constructed and
-
Mach’s principle-based model of the origin of mass Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-23 Yu-Jie Chen, Yuan-Yuan Liu, Yu-Zhu Chen, Wen-Du Li, Wu-Sheng Dai
In this paper, we present a Mach’s principle-based model of the origin of mass. According to Mach’s principle, the mass of matter arises from the coupling with the rest of the Universe rather than being an inherent property of matter itself. This model, in a sense, provides a model realization of Mach’s principle. In this model, the mass of matter is determined by spacetime. We illustrate the model
-
The radiant massive magnetic dipole Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-21 José Diaz Polanco, José Ayala Hoffmann, Maximiliano Ujevic
We present an exact, time-dependent solution for the Einstein field equations that models the coupling between an anisotropic fluid and a magnetic field in an axially symmetric space-time. By carefully selecting the metric components, we achieve a convenient separation of variables that enables us to solve Einstein’s field equations and obtain a solution that evolves into the Gutsunaev–Manko massive
-
Robinson–Trautman solutions with scalar hair and Ricci flow Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-21 Masato Nozawa, Takashi Torii
The vacuum Robinson–Trautman solution admits a shear-free and twist-free null geodesic congruence with a nonvanishing expansion. We perform a comprehensive classification of solutions exhibiting this property in Einstein’s gravity with a massless scalar field, assuming that the solution belongs at least to Petrov-type II and some of the components of Ricci tensor identically vanish. We find that these
-
The scattering map on collapsing charged spherically symmetric spacetimes Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-20 Fred Alford
In this paper we generalise our previous results (Alford 2020 Ann. Inst. Henri Poincare 21 2031–92) concerning scattering on the exterior of collapsing dust clouds to the charged case, including in particular the extremal case. We analyse the energy boundedness of solutions φ to the wave equation on the exterior of collapsing spherically symmetric charged matter clouds. We then proceed to define the
-
Scalar-multi-tensor approach to fT,B,∇μT,∇μB teleparallel gravity Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-16 E M B Assencio, P J Pompeia
In this work we analyze, in the context of modified teleparallel gravity, the equivalence between scalar-vector-tensor theories and geometrical theories of the type fT,B,∇μT,∇μB , where T and B are respectively the scalar torsion and the boundary scalar. This analysis is performed in the Jordan and Einstein frames. In particular, in the latter frame, two distinct cases are analyzed, where the role
-
Nested solutions of gravitational condensate stars Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-15 Daniel Jampolski, Luciano Rezzolla
Black holes are normally and naturally associated to the end-point of gravitational collapse. Yet, alternatives have been proposed and a particularly interesting one is that of gravitational condensate stars, or gravastars. We here revisit the gravastar model and increase the degree of speculation by considering new solutions that are inspired by the original model of gravastars with anisotropic pressure
-
General-relativistic wave–particle duality with torsion Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-14 Francisco Ribeiro Benard Guedes, Nikodem Janusz Popławski
We propose that the four-velocity of a Dirac particle is related to its relativistic wave function by ui=ψˉγiψ/ψˉψ . This relativistic wave–particle duality relation is demonstrated for a free particle related to a plane wave in a flat spacetime. For a curved spacetime with torsion, the momentum four-vector of a spinor is related to a generator of translation, given by a covariant derivative. The spin
-
On the space of compact diamonds of Lorentzian length spaces Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-14 Waldemar Barrera, Luis Montes de Oca, Didier A Solis
In this work we introduce the taxicab and uniform products for Lorentzian pre-length spaces. We further use these concepts to endow the space D(R×TX) of causal diamonds with a Lorentzian length space structure, closely relating its causal properties with its geometry as a metric space furnished with its associated Hausdorff distance. Among the general results, we show that this space is geodesic and
-
Laser frequency stabilization with the use of homodyne quadrature interferometers Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-13 C Di Fronzo, N A Holland, A L Mitchell, S J Cooper, M Valentini, D Martynov, L Prokhorov, C M Mow-Lowry
Laser frequency stabilization is a crucial technique for precision metrology. We demonstrate laser frequency control using a compact, interferometric sensor, specially modified for sensitivity to laser frequency noise. This setup achieves a balance between compact size, ease of use, and affordability. We stabilize the laser frequency noise, of a low-cost solid-state laser, to 4.5 kHz Hz−1 at 1 Hz
-
Tilt-to-length coupling noise suppression based on transformation of q parameters of Gaussian beams in spaceborne gravitational wave detection Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-13 Jinsong Liu, Xin Xu, Yidong Tan
Suppression of the coupling of unavoidable angular spacecraft jitter into the longitudinal displacement measurement, known as tilt-to-length (TTL) coupling, is crucial for realizing the required sensitivity of picometer /Hz1/2 level within the frequency range of 1 mHz–1 Hz in spaceborne gravitational wave detection. In this paper, we propose a novel method to suppress the TTL coupling between two Gaussian
-
Thermodynamics and optical properties of phantom AdS black holes in massive gravity Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-13 Kh Jafarzade, B Eslam Panah, M E Rodrigues
Motivated by high interest in Lorentz invariant massive gravity models known as dRGT massive gravity, we present an exact phantom black hole solution in this theory of gravity and discuss the thermodynamic structure of the black hole in the canonical ensemble. Calculating the conserved and thermodynamic quantities, we check the validity of the first law of thermodynamics and the Smarr relation in the
-
Implication of nano-Hertz stochastic gravitational wave on dynamical dark matter through a dark first-order phase transition Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-13 Siyu Jiang, Aidi Yang, Jiucheng Ma, Fa Peng Huang
For the first time, the expected stochastic gravitational wave background is probably discovered after observing the Hellings Downs correlation curve by several pulsar timing array (PTA) collaborations around the globe including NANOGrav, European PTA, Parkes PTA, and Chinese PTA. These new observations can help to explore or constrain the dark matter (DM) formation mechanisms in the early Universe
-
Scattering amplitudes for self-force Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-12 Tim Adamo, Andrea Cristofoli, Anton Ilderton, Sonja Klisch
The self-force expansion allows the study of deviations from geodesic motion due to the emission of radiation and its consequent back-reaction. We investigate this scheme within the on-shell framework of semiclassical scattering amplitudes for particles emitting photons or gravitons on a static, spherically symmetric background. We first present the exact scalar two-point amplitudes for Coulomb and
-
The non-linear perturbation of a black hole by gravitational waves. III. Newman–Penrose constants Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-12 J Frauendiener, A Goodenbour, C Stevens
In this paper we continue our study of the non-linear response of a Schwarzschild black hole to an ingoing gravitational wave by computing the Newman–Penrose (NP) constants. The NP constants are five complex, supertranslation-invariant quantities defined on null infinity I+ and although put forward in the 60’s, they have never been computed in a non-stationary setting. We accomplish this through a
-
Instability of a Kerr-type naked singularity due to light and matter accretion and its shadow Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-12 Aydin Tavlayan, Bayram Tekin
We study null and timelike constant radii geodesics in the environment of an over-spinning putative Kerr-type naked singularity. We are particularly interested in two topics: first, the differences of the shadows of the naked rotating singularity and the Kerr black hole; and second, the spinning down effect of the particles falling from the accretion disk. Around the naked singularity, the non-equatorial
-
EVStabilityNet: predicting the stability of star clusters in general relativity Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-09 Christopher Straub, Sebastian Wolfschmidt
We present a deep neural network which predicts the stability of isotropic steady states of the asymptotically flat, spherically symmetric Einstein–Vlasov system in Schwarzschild coordinates. The network takes as input the energy profile and the redshift of the steady state. Its architecture consists of a U-Net with a dense bridge. The network was trained on more than ten thousand steady states using
-
ΛCDM-Rastall cosmology revisited: constraints from a recent Quasars datasample Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-09 J A Astorga-Moreno, Kyra Jacobo, Salvador Arteaga, Miguel A García-Aspeitia, A Hernández-Almada
In this paper we study the impact of a recent quasar datasample in the constraint of the free parameters of an extension of general relativity. As a ruler to test, we use Rastall gravity in the context of background cosmology being a simple extension to general relativity. We compare the results from quasars dataset with other known samples such as cosmic chronometers, supernovae of the Ia type, baryon
-
A quantum of information in black hole evaporation Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-08 Maurice H P M van Putten
Black holes evolve by evaporation of their event horizon. While this process is believed to be unitary, there is no consensus on the recovery of information in black hole entropy. A missing link is a quantum of information in black hole evaporation. Distinct from Hawking radiation, we identify evaporation in entangled pairs by P2 topology of the event horizon consistent with the Bekenstein–Hawking
-
Deformations of the Kerr-(A)dS near horizon geometry Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-08 Eric Bahuaud, Sharmila Gunasekaran, Hari K Kunduri, Eric Woolgar
We investigate deformations of the Kerr-(A)dS near horizon geometry and derive partial infinitesimal rigidity results for it. The proof comprises two parts. First, we follow the analysis of Jezierski and Kamiński (2013 Gen. Rel. Grav. 45 987–1004) to eliminate all but a finite number of Fourier modes of linear perturbations. In the second part, we give an argument using analyticity to prove that there
-
Quasinormal mode spectrum of the AdS black hole with the Robin boundary condition Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-06 Shunichiro Kinoshita, Tomohiro Kozuka, Keiju Murata, Keita Sugawara
We study the quasinormal mode (QNM) spectrum of an asymptotically AdS black hole with the Robin boundary condition at infinity. We consider the Schwarzshild-AdS4 with the flat event horizon as the background spacetime and study its scalar field perturbation. Denoting leading coefficients of slow- and fast-decay modes of the scalar field at infinity as φ 1 and φ 2, respectively, we assume a linear relation
-
Anatomy of parameter-estimation biases in overlapping gravitational-wave signals Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-06 Ziming Wang, Dicong Liang, Junjie Zhao, Chang Liu, Lijing Shao
In future gravitational-wave (GW) detections, a large number of overlapping GW signals will appear in the data stream of detectors. When extracting information from one signal, the presence of other signals can cause large parameter estimation biases. Using the Fisher matrix (FM), we develop a bias analysis procedure to investigate how each parameter of other signals affects the inference biases. Taking
-
(Regular) Black holes in conformal Killing gravity coupled to nonlinear electrodynamics and scalar fields Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-06 José Tarciso S S Junior, Francisco S N Lobo, Manuel E Rodrigues
In this work, we explore new solutions with static and spherical symmetry in 4D for black holes and regular black holes in the recently proposed conformal Killing gravity (CKG). This theory is of third order in the derivatives of the metric tensor and essentially satisfies three theoretical criteria for gravitational theories beyond general relativity (GR). The criteria essentially stipulate the following
-
Inflation alternative via the gravitational field of a singularity Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-06 Michael Zlotnikov
We explore the scenario that the observable Universe emerged from the vicinity of a negative mass ring singularity, and all content of the Universe travels at the same group velocity close to the speed of light on a geodesic trajectory along the axis of rotation of the singularity. In appropriate coordinate parametrization and evaluated on the trajectory, we find that the metric tensor in the vicinity
-
Static spherically symmetric solutions in new general relativity Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-06 Alexey Golovnev, A N Semenova, V P Vandeev
We give a pedagogical introduction to static spherically symmetric solutions in models of New GR, both explaining the basics and showing how all such vacuum solutions can be obtained in elementary functions. In doing so, we coherently introduce the full landscape of these modified teleparallel spacetimes, and find a few special cases. The equations of motion are turned into a very nice and compact
-
Hairy black holes, scalar charges and extended thermodynamics Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-05 Romina Ballesteros, Tomás Ortín
We explore the use of the recently defined scalar charge which satisfies a Gauss law in stationary spacetimes, in the context of theories with a scalar potential. We find new conditions that this potential has to satisfy in order to allow for static, asymptotically-flat black-hole solutions with regular horizons and non-trivial scalar field. These conditions are equivalent to some of the known ‘no-hair’
-
Conformally Einstein Lorentzian Lie groups: extensions of the Euclidean and Poincaré groups Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-02 Esteban Calviño-Louzao, Eduardo García-Río, Ixchel Gutiérrez-Rodríguez, Ramón Vázquez-Lorenzo
We describe all Lorentzian semi-direct extensions of the Euclidean and Poincaré groups which are conformally Einstein.
-
Summing over non-singular paths in quantum cosmology Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-02 Hiroki Matsui
In this paper we provide the DeWitt propagator and its wave function in quantum cosmology using the path integral formulation of quantum gravity. The DeWitt boundary condition is introduced as a way to avoid the Big Bang singularity by positing that the wave function of the Universe vanishes near the Big Bang. However, there is currently no clear definition of the DeWitt boundary condition in the path
-
Detection of anomalies amongst LIGO’s glitch populations with autoencoders Classical Quant. Grav. (IF 3.5) Pub Date : 2024-02-01 Paloma Laguarta, Robin van der Laag, Melissa Lopez, Tom Dooney, Andrew L Miller, Stefano Schmidt, Marco Cavaglia, Sarah Caudill, Kurt Driessens, Joël Karel, Roy Lenders, Chris Van Den Broeck
Gravitational wave (GW) interferometers are able to detect a change in distance of ~1/10 000th the size of a proton. Such sensitivity leads to large rates of non-gaussian, transient bursts of noise, also known as glitches, which hinder the detection and parameter estimation of short- and long-lived GW signals in the main detector strain. Glitches, come in a wide range of frequency-amplitude-time morphologies
-
Gravitational traces of bumblebee gravity in metric–affine formalism Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-31 A A Araújo Filho, H Hassanabadi, N Heidari, J Kr̆íz̆, S Zare
This work explores various manifestations of bumblebee gravity within the metric–affine formalism. We investigate the impact of the Lorentz violation parameter, denoted as X, on the modification of the Hawking temperature. Our calculations reveal that as X increases, the values of the Hawking temperature attenuate. To examine the behavior of massless scalar perturbations, specifically the quasinormal
-
Remnant loop quantum black holes Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-31 H A Borges, I P R Baranov, F C Sobrinho, S Carneiro
Polymer models inspired by Loop Quantum Gravity (LQG) have been used to describe non-singular quantum black holes with spherical symmetry, with the classical singularity replaced by a transition from a black hole to a white hole. A recent model, with a single polymerisation parameter, leads to a symmetric transition with same mass for the black and white phases, and to an asymptotically flat exterior
-
Computational complexity in analogue gravity Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-30 Shahrokh Parvizi, Mojtaba Shahbazi
Analogue gravity helps to find some gravitational systems which are similar to the evolution of perturbation in condensed matter systems. These analogies provide a very good tool for either side. In other words, some aspects of gravity could be simulated in condensed matter laboratories. In this study, we find an interpretation for computational complexity in condensed matter systems in terms of the
-
The particle dynamics around rotating charged black holes with Weyl corrections Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-29 Rehana Rahim, Aqeela Razzaq, Muhammad Abdul Mateen
In this article, particle dynamics around charged rotating black holes with Weyl corrections is discussed. First, the metric is studied for its horizon structure and scalar curvature invariants. The effects of Weyl corrections on circular motion of the particles is analyzed around central object. We have shown dependency of effective potential, energy, angular momentum and inner most stable circular
-
Cosmology from the vacuum Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-23 Stefano Antonini, Petar Simidzija, Brian Swingle, Mark Van Raamsdonk
We argue that standard tools of holography can be used to describe fully non-perturbative microscopic models of cosmology in which a period of accelerated expansion may result from the positive potential energy of time-dependent scalar fields evolving towards a region with negative potential. In these models, the fundamental cosmological constant is negative, and the Universe eventually recollapses
-
Towards quantum mechanics on the curved cotangent bundle Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-23 Fabian Wagner
The minimal-length paradigm is a cornerstone of quantum gravity phenomenology. Recently, it has been demonstrated that minimal-length quantum mechanics can alternatively be described as an undeformed theory set on a nontrivial momentum space. However, there is no fully consistent formulation of these theories beyond Cartesian coordinates in flat space and, in particular, no position representation
-
On the (Non)Hadamard property of the SJ state in a 1+1 D causal diamond Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-23 Yifeng Rocky Zhu, Yasaman K Yazdi
The Sorkin–Johnston (SJ) state is a candidate physical vacuum state for a scalar field in a generic curved spacetime. It has the attractive feature that it is covariantly and uniquely defined in any globally hyperbolic spacetime, often reflecting the underlying symmetries if there are any. A potential drawback of the SJ state is that it does not always satisfy the Hadamard condition. In this work,
-
Gravitational waves from neutron-star mountains Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-23 Fabian Gittins
Rotating neutron stars that support long-lived, non-axisymmetric deformations known as mountains have long been considered potential sources of gravitational radiation. However, the amplitude from such a source is very weak and current gravitational-wave interferometers have yet to witness such a signal. The lack of detections has provided upper limits on the size of the involved deformations, which
-
Charged Lifshitz black holes from general covariance breaking Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-23 D C Moreira, A S Lemos, F A Brito
In this work we use a general covariance breaking mechanism to obtain a class of charged black holes whose background geometry asymptotically approaches Lifshitz spacetimes. We discuss how this method affects Einstein’s equations and explore the thermodynamics and critical behavior of the solution found.
-
Hamiltonian formulation of gravity as a spontaneously-broken gauge theory of the Lorentz group Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-23 Mehraveh Nikjoo, Tom Zlosnik
A number of approaches to gravitation have much in common with the gauge theories of the standard model of particle physics. In this paper, we develop the Hamiltonian formulation of a class of gravitational theories that may be regarded as spontaneously-broken gauge theories of the complexified Lorentz group SO(1,3)C with the gravitational field described entirely by a gauge field valued in the Lie
-
A deep learning technique to control the non-linear dynamics of a gravitational-wave interferometer Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-22 Peter Xiangyuan Ma, Gabriele Vajente
In this work we developed a deep learning technique that successfully solves a non-linear dynamic control problem. Instead of directly tackling the control problem, we combined methods in probabilistic neural networks and a Kalman-filter-inspired model to build a non-linear state estimator for the system. We then used the estimated states to implement a trivial controller for the now fully observable
-
Slowly rotating ultra-compact Schwarzschild star in the gravastar limit Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-19 Philip Beltracchi, Camilo Posada
We reconsider the problem of a slowly rotating homogeneous star, or Schwarzschild star, when its compactness goes beyond the Buchdahl bound and approaches the gravastar limit R→2M . We compute surface and integral properties of such configuration by integrating the Hartle–Thorne structure equations for slowly rotating relativistic masses, at second order in angular velocity. In the gravastar limit
-
Quantization of spinor field in the Schwarzschild spacetime and spin sums for solutions of the Dirac equation Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-19 Vadim Egorov, Mikhail Smolyakov, Igor Volobuev
We discuss the problem of canonical quantization of a free massive spinor field in the Schwarzschild spacetime. It is shown that a consistent procedure of canonical quantization of the field can be carried out without taking into account the internal region of the black hole, the canonical commutation relations in the resulting theory hold exactly and the Hamiltonian has the standard form. Spin sums
-
Barrow holographic dark energy in Brane world cosmology Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-18 Anirban Chanda, Arpan Krishna Mitra, Sagar Dey, Souvik Ghose, B C Paul
Cosmological features of barrow holographic dark energy (BHDE), a recent generalization of original Holographic dark energy (DE) with a richer structure, are studied in the context of Dvali–Gabadadze–Porrati (DGP) brane, Randall and Sundrum (RS II) brane-world, and the cyclic Universe. It is found that a flat FRW scenario with pressure less dust and a DE component described as BHDE can accommodate
-
Non-canonical Higgs inflation Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-18 Pooja Pareek, Akhilesh Nautiyal
The large value of non-minimal coupling constant ξ required to satisfy cosmic microwave background observations in Higgs inflation violates unitarity. In this work we study Higgs-inflation with non-canonical kinetic term of DBI form to find whether ξ can be reduced. To study the inflationary dynamics, we transform the action to the Einstein frame, in which the Higgs is minimally coupled to gravity
-
Absorption cross section in gravity’s rainbow from confluent Heun equation Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-18 Julián Barragán Amado, Kihong Kwon, Bogeun Gwak
We investigate the scattering of a massless scalar field by a charged, non-rotating black hole in the presence of gravity’s rainbow. Using the connection coefficients of the confluent Heun equation expressed in terms of the semi-classical confluent conformal blocks and the instanton part of the Nekrasov–Shatashvili free energy, we obtain an asymptotic expansion for the low-energy absorption cross section
-
Topology-induced quantum transition in multiparticle systems in vicinity of a black hole Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-18 J E Jacak
The qualitative change of the type of particle trajectory homotopy in close vicinity of general-relativistic gravitational singularity affects quantum statistics in systems of identical indistinguishable particles at passing the photon sphere rim of a Schwarzschild black hole. This causes a local departure from the Pauli exclusion principle, which results in some high energy effects manifesting themselves
-
Modified measures as an effective theory for causal fermion systems Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-18 Felix Finster, Eduardo Guendelman, Claudio F Paganini
We compare the structures of the theory of causal fermion systems (CFS), an approach to unify quantum theory with general relativity (GR), with those of modified measure theories (MMT), which are a set of modified gravity theories. Classical spacetimes with MMT can be obtained as the continuum limit of a CFS. This suggests that MMT could serve as effective descriptions of modifications to GR implied
-
A possible solution to the Hubble tension from quantum gravity Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-16 Anupama B, P K Suresh
We investigate the relevance of quantum gravity during inflation to address the Hubble tension that arises from Planck 2018 and supernova H0 for the equation of state data sets. We show that the effect of quantum gravity during inflation can increase the rate of change of H0 , thereby accounting for a wide range of observed H0 . Further, we show that due to the quantum gravity effect on inflation,
-
A classical firewall transformation as a canonical transformation Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-10 Nathaniel A Strauss, Bernard F Whiting
The firewall transformation put forward by ’t Hooft in recent years has made ambitious claims of solving the firewall problem and the black hole information paradox while maintaining unitary evolution. However, the theory has received limited attention from the community, especially in regards to its foundations in purely classical gravitational physics. This paper investigates the underlying assumptions
-
AdS3 Einstein gravity and boundary description: pedagogical review Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-04 Chen-Te Ma
We review the various aspects of the 3D Einstein gravity theory with a negative cosmological constant and its boundary description. We also explore its connections to conformal field theories (CFTs), modular symmetry, and holography. It is worth noting that this particular theory is topological in nature, which means that all the physical degrees of freedom are located on the boundary. Additionally
-
Joint optimization of seismometer arrays for the cancellation of Newtonian noise from seismic body waves in the Einstein Telescope Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-04 Francesca Badaracco, Jan Harms, Luca Rei
Seismic Newtonian noise (NN) is predicted to limit the sensitivity of the Einstein Telescope (ET). It can be reduced with coherent noise cancellation techniques using data from seismometers. To achieve the best results, it is important to place the seismic sensors in optimal positions. A preliminary study on this topic was conducted for the ET: it focused on the optimization of the seismic array for
-
Fully consistent rotating black holes in the cubic Galileon theory Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-04 P Grandclément
Configurations of rotating black holes in the cubic Galileon theory are computed by means of spectral methods. The equations are written in the 3+1 formalism and the coordinates are based on the maximal slicing condition and the spatial harmonic gauge. The black holes are described as apparent horizons in equilibrium. It enables the first fully consistent computation of rotating black holes in this
-
On the gravitational precession memory effect for an ensemble of gyroscopes Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-04 Raihaneh Moti, Ali Shojai
We study the thermodynamic properties of a freely falling ensemble of gyroscopes after the passage of a weak gravitational wave. Due to the precession memory effect, the thermodynamic quantities will experience a change because of the space-time perturbation. We discuss that this GravoThermo memory effect potentially can be used for the detection of the gravitational waves.
-
General spherically symmetric solution of Cotton gravity Classical Quant. Grav. (IF 3.5) Pub Date : 2024-01-04 Merab Gogberashvili, Ani Girgvliani
In this paper we present the general spherically symmetric static solution to the vacuum equations of Cotton gravity. The obtained metric solution reveals the presence of singularities at the photosphere of a spherical source, which probably obstruct the formation of the stellar Schwarzschild-radius black holes. The solution is characterized by two integration constants, whose values can be restricted
-
Thin tubes of a massless scalar field as a possible source of dark energy Classical Quant. Grav. (IF 3.5) Pub Date : 2023-12-29 Alexander Lelyakov, Stepan Lelyakov
In the proposed work, we have investigated the possibility of using an ideal gas of thin tubes of a massless scalar field as a source of Dark Energy. If we assume the homogeneity and isotropy of such an ideal gas, then its equation of state can be estimated by examining the gravitational field of a solitary tube of a scalar field. We have studied the gravitational field of a thin axially symmetric
-
Real supersymmetric solutions of (3,2) signature five-dimensional supergravity Classical Quant. Grav. (IF 3.5) Pub Date : 2023-12-28 D Farotti, J B Gutowski, W A Sabra
We classify supersymmetric solutions of D = 5 (3,2) signature supergravity with either vanishing or imaginary gauge coupling constant preserving the minimal N = 2 supersymmetry. We prove that the geometry of such solutions is characterized by a nilpotent integrable endomorphism, and obtain the necessary and sufficient conditions on the fluxes imposed by supersymmetry. We also construct examples of
-
Fractional cosmic strings Classical Quant. Grav. (IF 3.5) Pub Date : 2023-12-28 Sébastien Fumeron, Malte Henkel, Alexander López
Topological defects are investigated in the framework of quantum gravity models based on the hypothesis of an effective fractal dimension of the Universe. From a minimal coupling procedure, the tools of fractional calculus are used to determine the geometry associated to a fractional cosmic string. Several results for the propagation of light are discussed, notably the light-deviation angle due to
-
Adapting the PyCBC pipeline to find and infer the properties of gravitational waves from massive black hole binaries in LISA Classical Quant. Grav. (IF 3.5) Pub Date : 2023-12-27 Connor R Weaving, Laura K Nuttall, Ian W Harry, Shichao Wu, Alexander Nitz
The laser interferometer space antenna (LISA), due for launch in the mid 2030s, is expected to observe gravitational waves (GWs) from merging massive black hole binaries (MBHBs). These signals can last from days to months, depending on the masses of the black holes, and are expected to be observed with high signal to noise ratios (SNRs) out to high redshifts. We have adapted the PyCBC software package
-
Role of substrate and TiO2 content in TiO2:Ta2O5 coatings for gravitational wave detectors Classical Quant. Grav. (IF 3.5) Pub Date : 2023-12-27 Ofelia Durante, Veronica Granata, Michele Magnozzi, Alex Amato, Christophe Michel, Laurent Pinard, Massimo Granata, Maurizio Canepa, Giovanni Carapella, Francesco Chiadini, Roberta De Simone, Rosalba Fittipaldi, Vincenzo Fiumara, Vincenzo Pierro, Innocenzo M Pinto, Antonio Vecchione, Fabrizio Bobba, Cinzia Di Giorgio
Gravitational wave detectors (GWDs) are designed to detect the elusive signals produced by spacetime ripples, the GWs. The key to improving GWD sensitivity relies on the reduction of the thermal noise introduced by the mirrors. The high refractive index component of the high-reflectance mirrors installed in the current generation GWDs, such as Advanced LIGO and Advanced Virgo, is made of a mixture
-
Path integral factorization and the gravitational effective action Classical Quant. Grav. (IF 3.5) Pub Date : 2023-12-27 Patrick Draper, Szilard Farkas, Manthos Karydas
We discuss the factorization and continuity properties of fields in the Euclidean gravitational path integral with higher dimension operators constructed from powers of the Riemann tensor. We construct the boundary terms corresponding to the microcanonical ensemble and show that the saddle point approximation to the path integral with a quasilocal energy constraint generally yields a saddle point with