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Clock synchronization and light-travel-time estimation for space-based gravitational-wave detectors Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-17 Jan Niklas Reinhardt, Olaf Hartwig and Gerhard Heinzel
Space-based gravitational-wave detectors, such as the Laser Interferometer Space Antenna (LISA), record interferometric measurements on widely separated satellites. Their clocks are not synced actively. Instead, clock synchronization is performed in on-ground data processing. It relies on measurements of the so-called pseudoranges, which entangle the interspacecraft light travel times (LTTs) with the
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Advanced charge control dynamics simulation for the LISA gravitational reference sensor Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-17 Samantha Parry Kenyon, Stephen Apple, John Siu, Peter J Wass and John W Conklin
A gravitational wave detector in space, the Laser Interferometer Space Antenna (LISA) will be able to detect gravitational waves in the frequency range of 0.1 mHz–1 Hz, adding to humanity’s knowledge of the dark cosmos. The LISA gravitational reference sensor contains a test mass (TM) and is used to determine the local inertial reference frame and as endpoints for the interferometry. The TM is surrounded
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Spikes and spines in 3D Lorentzian simplicial quantum gravity Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-17 Johanna Borissova, Bianca Dittrich, Dongxue Qu and Marc Schiffer
Simplicial approaches to quantum gravity such as Quantum Regge Calculus and Spin Foams include configurations where bulk edges can become arbitrarily large while keeping the lengths of the boundary edges small. Such configurations pose significant challenges in Euclidean Quantum Regge Calculus, as they lead to infinities for the partition function and length expectation values. Here we investigate
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Probing the axion–photon coupling with space-based gravitational wave detectors Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-17 Jordan Gué, Aurélien Hees and Peter Wolf
We propose a simple modification of space-based gravitational wave (GW) detector optical benches which would enable the measurement of vacuum birefringence of light induced by axion dark matter through its coupling to electromagnetism. Specifically, we propose to change a half-wave plate by a circular polarizer. While marginally affecting the sensitivity to GW by a factor , we show that such an adjustment
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A new approach in classical Klein–Gordon cosmology: ‘Small Bangs’, inflation and Dark Energy Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-14 Eleni-Alexandra Kontou, Nicolai Rothe
In this work, we analyze the cosmological model in which the expansion is driven by a classical, free Klein–Gordon field on a flat, four-dimensional Friedmann–Lemaître—Robertson–Walker spacetime. The model allows for arbitrary mass, non-zero cosmological constant and coupling to curvature. We find that there are strong restrictions to the parameter space, due to the requirement for the reality of the
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Detecting kHz gravitons from a neutron star merger with a multi-mode resonant mass detector Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-14 Germain Tobar, Igor Pikovski, Michael E Tobar
We propose a multi-mode bar consisting of mass elements of decreasing size for the implementation of a gravitational version of the photo-electric effect through the stimulated absorption of up to kHz gravitons from a binary neutron star merger and post-merger. We find that the multi-mode detector has normal modes that retain the coupling strength to the gravitational wave of the largest mass-element
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Spatial curvature in coincident gauge f(Q) cosmology Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-13 Erik Jensko
In this work we study the Friedmann–Lemaître–Robertson–Walker cosmologies with arbitrary spatial curvature for the symmetric teleparallel theories of gravity, giving the first presentation of their coincident gauge form. Our approach explicitly starts with the cosmological Killing vectors and constructs the coincident gauge coordinates adapted to these Killing vectors. We then obtain three distinct
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Why the universal threshold for primordial black hole formation is universal Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-13 Alex Kehagias, Davide Perrone, Antonio Riotto
We show why the threshold for primordial black hole formation is universal (independent from the shape of the perturbation) when expressed in terms of the volume averaged compaction function. The proof is rooted in the self-similarity of the gravitational collapse phenomenon at criticality.
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Probing cosmic chemical enrichment with next-generation gravitational-wave observatories Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-12 Maya Fishbach
By observing binary black hole (BBH) mergers out to the edge of the Universe, next-generation (XG) ground-based gravitational-wave detectors like Cosmic Explorer and Einstein Telescope will map the BBH merger rate across all of cosmic history. This merger rate traces the formation rate of their progenitor stars convolved with a delay time distribution. Given theoretically-motivated priors on the delay
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Revisiting the apparent horizon finding problem with multigrid methods Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-11 Hon-Ka Hui, Lap-Ming Lin
Apparent horizon plays an important role in numerical relativity as it provides a tool to characterize the existence and properties of black holes on three-dimensional spatial slices in 3+1 numerical spacetimes. Apparent horizon finders based on different techniques have been developed. In this paper, we revisit the apparent horizon finding problem in numerical relativity using multigrid-based algorithms
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Plane-parallel waves as Jacobi–Lie models Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-11 Ivo Petr, Ladislav Hlavatý
T-duality and its generalizations are widely recognized either as symmetries or solution-generating techniques in string theory. Recently introduced Jacobi–Lie T-plurality is based on Leibniz algebras whose structure constants fabc,fcab,Za,Za satisfy further conditions. Low dimensional Jacobi–Lie bialgebras were classified a few years ago. We study four- and six-dimensional algebras with structure
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Einstein–Klein–Gordon system via Cauchy-characteristic evolution: computation of memory and ringdown tail Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-11 Sizheng Ma, Kyle C Nelli, Jordan Moxon, Mark A Scheel, Nils Deppe, Lawrence E Kidder, William Throwe, Nils L Vu
Cauchy-characteristic evolution (CCE) is a powerful method for accurately extracting gravitational waves at future null infinity. In this work, we extend the previously implemented CCE system within the numerical relativity code SpECTRE by incorporating a scalar field. This allows the system to capture features of beyond-general-relativity theories. We derive scalar contributions to the equations of
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Spherically symmetric and static black bounces with multiple horizons, throats, and anti-throats in four dimensions Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-10 Manuel E Rodrigues, Marcos V de S Silva
Black bounce (BB) spacetimes usually arise from the Simpson–Visser regularization method. This type of metric presents a wormhole throat inside an event horizon. In this paper, we presented new classes of BB spacetime solutions, which have multiple horizons, throats, and anti-throats. These solutions are variants of black holes and wormholes, based on modifications of the Schwarzschild and Simpson–Visser
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A primer on Carroll gravity Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-10 Eleanor March, James Read
The ultra-relativistic limit of general relativity is Carroll gravity. In this article, we provide (i) a rigorous and thorough exposition of the geometric formalism of the ‘magnetic’ version of Carroll gravity, (ii) a presentation of this theory as a limit of general relativity in a geometrical, ‘lightcone-narrowing’ sense, and (iii) an exploration of some of the various conceptually interesting features
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Eisenhart lift for scalar fields in the FLRW universe Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-07 Takeshi Chiba, Tsuyoshi Houri
The Eisenhart lift of Riemannian type describes the motion of a particle as a geodesic in a higher-dimensional Riemannian manifold with one additional coordinate. It has recently been generalized to a scalar field system by introducing one additional vector field. We apply this approach to a scalar field system in the Friedmann–Lemaitre–Robertson–Walker universe and classify the symmetries of the system
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Relating gauge gravity to string theory through obstruction Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-07 Casey Cartwright, Alex Flournoy
In this article we provide a more detailed account of the geometry and topology of the composite bundle formalism introduced by Tresguerres (2002 Phys. Rev. D 66 064025) to accommodate gravitation as a gauge theory. In the first half of the article we identify a global structure required by the composite construction which not only exposes how the ordinary frame and tangent bundle expected in general
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Simulated alignment method for suppressing tilt-to-length coupling noise in space gravitational wave telescopes Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-07 Lanjun Huang, Miao Yu, Yanxiong Wu, Jiancong Li, Hongbo Li, Donglan Zou, Yinghong Liu, Lintong Lin
Space gravitational wave telescopes are critical in achieving precise interstellar laser interferometry. The coupling coefficient is a key metric for evaluating the ultimate performance of a telescope. However, alignment errors during the assembly phase can degrade the wavefront quality of the telescope, intensify coupling noise, and impair overall performance. Currently, no alignment scheme specifically
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A control strategy for seismic noise reduction on advanced LIGO gravitational-wave detector Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-06 C Di Fronzo, J Driggers, J Warner, E Schwartz, B Lantz, A Pelé, S Biscans, C M Mow-Lowry, R Mittleman
The differential seismic motion between the internal seismic isolation platforms on the advanced laser interferometer gravitational wave observatory, affects the sensitivity of the detector at lower frequencies (below 1 Hz), because each platform moves independently. This induces noise inside the cavities of the auxiliary optics placed on the platforms, which translates into a higher control effort
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Constraining modified gravity models through strong lensing cosmography Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-05 Mario H Amante, Andrés Lizardo, Javier Chagoya, C Ortiz
We analyze cosmography as a tool to constrain modified gravity theories. We take four distinct models and obtain their parameters in terms of the cosmographic parameters favored by observational data of strong gravitational lensing. We contrast with the values obtained by direct comparison between each model and the observational data. In general, we find consistency between the two approaches at 2σ
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Quantum state tomography on closed timelike curves using weak measurements Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-05 Lachlan G Bishop, Fabio Costa, Timothy C Ralph
Any given prescription of quantum time travel necessarily endows a Hilbert space to the chronology-violating (CV) system on the closed timelike curve (CTC). However, under the two foremost models, Deutsch’s prescription (D-CTCs) and postselected teleportation (P-CTCs), the CV system is treated very differently: D-CTCs assign a definite form to the state on this system, while P-CTCs do not. To further
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Fluctuations and correlations in causal set theory Classical Quant. Grav. (IF 3.6) Pub Date : 2025-02-05 Heidar Moradi, Yasaman K Yazdi, Miguel Zilhão
We study the statistical fluctuations (such as the variance) of causal set quantities, with particular focus on the causal set action. To facilitate calculating such fluctuations, we develop tools to account for correlations between causal intervals with different cardinalities. We present a convenient decomposition of the fluctuations of the causal set action into contributions that depend on different
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Gaussian orbital perturbation theory in Schwarzschild space-time in terms of elliptic functions Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-31 Oleksii Yanchyshen, Claus Lämmerzahl
General relativistic Gauss equations for osculating elements for bound orbits under the influence of a perturbing force in an underlying Schwarzschild space-time have been derived in terms of Weierstrass elliptic functions. Thereby, the perturbation forces are restricted to act within the orbital plane only. These equations are analytically solved in linear approximation for several different perturbations
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Revisiting gravitational angular momentum and mass dipole losses in the eikonal framework Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-31 Carlo Heissenberg, Rodolfo Russo
We review the description of classical gravitational scatterings of two compact objects by means of the eikonal framework. This encodes via scattering amplitudes both the motion of the bodies and the gravitational-wave signals that such systems produce. As an application, we combine the next-to-leading post-Minkowskian waveform derived in the post-Newtonian PN limit with the 4PM static loss due to
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Gravity from Pre-geometry Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-30 A Addazi, S Capozziello, A Marcianò, G Meluccio
The gravitational interaction, as described by the Einstein–Cartan theory, is shown to emerge as the by-product of the spontaneous symmetry breaking of a gauge symmetry in a pre-geometric four-dimensional spacetime. Starting from a formulation a` la Yang–Mills on an SO(1,4) or SO(3,2) principal bundle and not accounting for a spacetime metric, the Einstein–Hilbert action is recovered after the identification
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Measurements of Gravitational Attractions at small Accelerations Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-30 W Bartel, C W Elvers, L Jönsson, G Kempf, H Krause, B Loehr, E Lohrmann, H Meyer, P Steffen, E Wuensch
Gravitational interactions were studied by measuring the influence of small external field masses on a microwave resonator. It consisted of two spherical mirrors, which acted as independent pendulums individually suspended by strings. Two identical field masses were moved along the axis of the resonator symmetrically and periodically between a near and a far position. Their gravitational interaction
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Euclidean actions and static black hole entropy in teleparallel theories Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-30 Iberê Kuntz, Gregorio Paci, Omar Zanusso
It is well-known that the results by Bekenstein, Gibbons and Hawking on the thermodynamics of black holes can be reproduced quite simply in the Euclidean path integral approach to quantum gravity. The corresponding partition function is obtained semiclassically, ultimately requiring only the on-shell Einstein–Hilbert action with opportune asymptotic subtractions. We elaborate on the fact that the same
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Pushing limits: probing new gravity using a satellite constellation Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-30 Viktor T Toth
Building upon earlier work, we explore the limits of using a configuration of satellites to measure the trace of the gravitational gradient tensor using intersatellite laser ranging and timing observables without relying on high-precision external observables such as deep space radio navigation or astrometry with unrealistic accuracy. A refined model, calculated with extended numerical precision, confirms
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Primordial gravitational wave backgrounds from phase transitions with next generation ground based detectors Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-29 Chiara Caprini, Oriol Pujolàs, Hippolyte Quelquejay-Leclere, Fabrizio Rompineve, Danièle A Steer
Third generation ground-based gravitational wave (GW) detectors, such as Einstein Telescope and Cosmic Explorer, will operate in the (few−104) Hz frequency band, with a boost in sensitivity providing an unprecedented reach into primordial cosmology. Working concurrently with pulsar timing arrays in the nHz band, and LISA in the mHz band, these 3G detectors will be powerful probes of beyond the standard
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Test particles in Kaluza–Klein models Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-29 João Baptista
Geodesics in general relativity describe the behaviour of test particles in a gravitational field. In 5D Kaluza–Klein, geodesics reproduce the Lorentz force motion of particles in an electromagnetic field. This paper studies geodesic motion on a higher-dimensional M4×K with background metrics encoding general 4D gauge fields and Higgs-like scalars. It shows that the classical mass and charge of a test
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A physically modelled selection function for compact binary mergers in the LIGO-Virgo O3 run and beyond Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-29 Ana Lorenzo-Medina, Thomas Dent
Despite the observation of nearly 100 compact binary coalescence (CBC) events up to the end of the Advanced gravitational-wave (GW) detectors’ third observing run (O3), there remain fundamental open questions regarding their astrophysical formation mechanisms and environments. Population analysis should yield insights into these questions, but requires careful control of uncertainties and biases. GW
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Study on high-frequency quasi-periodic oscillations in rotating black bounce spacetime Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-27 Shining Yang, Jianbo Lu, Xinping Yu, Jingyang Xu
This study investigates the dynamical effects of particles orbiting a celestial body in rotating Simpson–Visser (RSV) spacetime. The results show that, compared to Kerr and rotating regular black holes, the innermost stable circular orbit of an RSV wormhole is closer to the central object. Using high-frequency quasi-periodic oscillation (HFQPO) data from microquasars and χ2 analysis, we constrain the
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Gravitational helicity flux density from two-body systems Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-27 Jiang Long, Run-Ze Yu
The helicity flux density is a novel quantity which characterizes the angle-dependence of the helicity of radiative gravitons and it may be tested by gravitational wave experiments in the future. We derive a quadrupole formula for the helicity flux density due to gravitational radiation in the slow motion and the weak field limit. We apply the formula to the bound and unbound orbits in two-body systems
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Automated alignment of an optical cavity using machine learning Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-24 Jiayi Qin, Katherine Kinder, Shreejit Jadhav, Praneel Chugh, Bram J J Slagmolen
Optimised alignment is important in optical systems, particularly in high-precision instrumentation such as gravitational wave detectors, in order to maximise the sensitivity. During operations, high performing optical wave-front sensing and feedback systems are used to maintain optical cavity performance. However, the need for an automated initial alignment process arises after maintenance or large
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Exploring null geodesic of Finslerian hairy black hole Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-24 Z Nekouee, S K Narasimhamurthy, B R Yashwanth, T Sanjay
The study of hairy black holes within Finsler space-time is performed based on a fundamental set of criteria. These requirements include the presence of a clearly defined event horizon and compliance with the strong energy condition for the characteristics outside the horizon. This examination is conducted through the gravitational decoupling method to describe the deformation of a Finslerian Schwarzschild
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Tilt-to-length coupling in LISA—uncertainty and biases Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-24 M-S Hartig, J Marmor, D George, S Paczkowski, J Sanjuan
The coupling of the angular jitter of the spacecraft and their sub-assemblies with the optical bench and the telescope into the interferometric length readout will be a major noise source in the LISA mission. We refer to this noise as tilt-to-length (TTL) coupling. It will be reduced directly by realignments, and the residual noise will then be subtracted in post-processing. The success of these mitigation
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Dynamical similarity in field theories Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-22 David Sloan
In previous work I have shown that Herglotz actions reproduce the dynamics of classical mechanical theories which exhibit dynamical similarities. Recent work has shown how to extend field theories in both the Lagrangian and de Donder-Weyl formalism to contact geometry (Gaset et al 2020 Ann. Phys., NY 414 168092; 2021 Rep. Math. Phys. 87 347–68; 2022 arXiv:2211.17058). In this article I show how dynamical
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Quantum curvature fluctuations and the cosmological constant in a single plaquette quantum gravity model Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-22 Samuel Blitz, Shahn Majid
Understanding the microscopic behavior of spacetime, in particular quantum uncertainty in the Ricci scalar, is critical for developing a theory of quantum gravity and perhaps solving the cosmological constant problem. To test this, we compute this quantity for a simple but exact discrete quantum gravity model based on a single plaquette of spacetime. Our results confirm initial speculations of Wheeler
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Quadrupolar power radiation by a binary system in a hyperbolic encounter on de Sitter background Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-20 Michael Blanc, Philippe Jetzer, Shubhanshu Tiwari
The present cosmological model and the surveys favor the Universe with a small but positive cosmological constant Λ, which accounts for dark energy and causes an exponential expansion. This can have observational consequences in the current detection of gravitational waves, as most of the waveforms for gravitational radiation are computed assuming a flat (Minkowski) background. In this work, we compute
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Flat space gravity at finite cutoff Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-20 Batoul Banihashemi, Edgar Shaghoulian, Sanjit Shashi
We study the thermodynamics of Einstein gravity with vanishing cosmological constant subjected to conformal boundary conditions. Our focus is on comparing the series of subextensive terms to predictions from thermal effective field theory, with which we find agreement for the boundary theory on a spatial sphere, hyperbolic space, and flat space. We calculate the leading Wilson coefficients and observe
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White paper and roadmap for quantum gravity phenomenology in the multi-messenger era Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-17 R Alves Batista, G Amelino-Camelia, D Boncioli, J M Carmona, A di Matteo, G Gubitosi, I Lobo, N E Mavromatos, C Pfeifer, D Rubiera-Garcia, E N Saridakis, T Terzić, E C Vagenas, P Vargas Moniz, H Abdalla, M Adamo, A Addazi, F K Anagnostopoulos, V Antonelli, M Asorey, A Ballesteros, S Basilakos, D Benisty, M Boettcher, J Bolmont, A Bonilla, P Bosso, M Bouhmadi-López, L Burderi, A Campoy-Ordaz, S Caroff
The unification of quantum mechanics and general relativity has long been elusive. Only recently have empirical predictions of various possible theories of quantum gravity been put to test, where a clear signal of quantum properties of gravity is still missing. The dawn of multi-messenger high-energy astrophysics has been tremendously beneficial, as it allows us to study particles with much higher
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Multimessenger observations and the science enabled: continuous waves and their progenitors, equation of state of dense matter Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-17 D I Jones, K Riles
Rotating and oscillating neutron stars can give rise to long-lived Continuous Gravitational Waves (CGWs). Despite many years of searching, the detection of such a CGW signal remains elusive. In this article we describe the main astrophysical uncertainties regarding such emission, and their relation to the behaviour of matter at extremely high density. We describe the main challenges in searching for
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On Carrollian and Galilean contractions of BMS algebra in 3 and 4 dimensions Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-17 Andrzej Borowiec, Jerzy Kowalski-Glikman, Tomasz Trześniewski
In this paper, we find a class of Carrollian and Galilean contractions of (extended) Bondi–van der Burg–Metzner–Sachs (BMS) algebra in 3+1 and 2+1 dimensions. To this end, we investigate possible embeddings of 3D/4D Poincaré into the BMS 3 and BMS 4 algebras, respectively. The contraction limits in the 2+1-dimensional case are then enforced by appropriate contractions of its Poincaré subalgebras. In
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Picometer sensitive prototype of the optical truss interferometer for LISA Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-13 Kylan Jersey, Harold Hollis, Han-Yu Chia, Jose Sanjuan, Paul Fulda, Guido Mueller, Felipe Guzman
The optical truss interferometer (OTI) is a contingent subsystem proposed for the LISA telescopes to aid in the verification of a 1pmHz optical path length stability. Each telescope would be equipped with three pairs of compact fiber-coupled units, each forming an optical cavity with a baseline proportional to the telescope length at different points around the aperture. Employing a Pound–Drever–Hall
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A non-local way around the no-global-symmetries conjecture in quantum gravity? Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-13 Johanna Borissova, Astrid Eichhorn, Shouryya Ray
The no-global-symmetries conjecture is central to the swampland program that delineates the boundary between effective field theories that can be obtained from a quantum theory of gravity to those that cannot. The conjecture states that virtual black-hole configurations in the path integral generate terms that violate all global symmetries in the effective action for matter. Because of its central
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Axion-like universal gravitational wave interpretation of pulsar timing array data Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-10 Kaloian D Lozanov, Shi Pi, Misao Sasaki, Volodymyr Takhistov, Ao Wang
Formation of cosmological solitons is generically accompanied by production of gravitational waves (GWs), with a universal GW background expected at frequency scales below that of non-linear dynamics. Beginning with a general phenomenological description of GWs associated with soliton formation, we demonstrate that universal GW background from axion-like particle solitonic oscillons provides a viable
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Entanglement entropy in quantum black holes Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-07 Alessio Belfiglio, Orlando Luongo, Stefano Mancini, Sebastiano Tomasi
We discuss the entanglement entropy for a massive scalar field in two Schwarzschild-like quantum black hole spacetimes, also including a nonminimal coupling term with the background scalar curvature. To compute the entanglement entropy, we start from the standard spherical shell discretization procedure, tracing over the degrees of freedom residing inside an imaginary surface. We estimate the free
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Simulating binary black hole mergers using discontinuous Galerkin methods Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-07 Geoffrey Lovelace, Kyle C Nelli, Nils Deppe, Nils L Vu, William Throwe, Marceline S Bonilla, Alexander Carpenter, Lawrence E Kidder, Alexandra Macedo, Mark A Scheel, Azer Afram, Michael Boyle, Andrea Ceja, Matthew Giesler, Sarah Habib, Ken Z Jones, Prayush Kumar, Guillermo Lara, Denyz Melchor, Iago B Mendes, Keefe Mitman, Marlo Morales, Jordan Moxon, Eamonn O’Shea, Kyle Pannone, Harald P Pfeiffer,
Binary black holes are the most abundant source of gravitational-wave observations. Gravitational-wave observatories in the next decade will require tremendous increases in the accuracy of numerical waveforms modeling binary black holes, compared to today’s state of the art. One approach to achieving the required accuracy is using spectral-type methods that scale to many processors. Using the SpECTRE
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New series expansion for the periapsis shift Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-07 Akihito Katsumata, Tomohiro Harada, Kota Ogasawara, Hayami Iizuka
We propose a prescription for a new series expansion of the periapsis shift. The prescription formulates the periapsis shift in various spacetimes analytically without using special functions and provides simple and highly accurate approximate formulae. We derive new series representations for the periapsis shift in the Kerr and the Chazy–Curzon spacetimes by using the prescription, where the expansion
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Phase space structure of symmetric teleparallel theory of gravity Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-07 Dalia Saha, Abhik Kumar Sanyal
The ‘generalized symmetric teleparallel gravity’ (GSTG) does not admit diffeomorphic invariance, since the auxiliary field as well as the shift vector act as non-propagating dynamical variables carrying 1/2 degrees of freedom each. We show that in a minisuperspace model, which is devoid of the shift vector, the problem is alleviated for locally Lorentz invariant GSTG theory, and diffeomorphic invariance
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Dimensional stability sensitivity analysis based on transfer function models for telescope in space gravitational wave detectors Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-07 Zihan Wang, Yanfu Liu, Xida Han, Yuntao Cheng, Ming Li, Hongchao Zhao
The telescope serves as a vital component of the space gravitational wave detector. In TianQin project, the exceptional dimensional stability of the telescope must be better than 1 pm Hz−1/2 @0.1 mHz–1 Hz. To assess the in-orbit dimensional stability of the telescope, a transfer function model was developed to evaluate the stability of the primary and secondary mirror spacing structure, considering
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Gyroscopic gravitational memory from quasi-circular binary systems Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-07 Guillaume Faye, Ali Seraj
Gravitational waves cause freely falling spinning objects to precess, resulting in a net orientation change called gyroscopic memory. In this paper, we will consider isolated gravitational sources in the post-Newtonian (PN) framework and compute the gyroscopic precession and memory at leading PN orders. We compare two competing contributions: the spin memory and the nonlinear helicity flux. At the
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Some remarks on Wang–Yau quasi-local mass Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-06 Bowen Zhao, Lars Andersson, Shing-Tung Yau
We review the definition of Wang–Yau quasi-local mass from the point of view of the gravitational Hamiltonian. This makes clear the relation between Wang–Yau definition and Brown–York or even global ADM definition. We make a brief comment on admissibility condition in the definition of the Wang–Yau quasi-lcoal mass. We extend the positivity proof for Wang–Yau quasi-local energy to allow possible presence
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3+1 formalism of the minimally extended varying speed of light model Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-06 Seokcheon Lee
The 3+1 formalism provides a structured approach to analyzing spacetime by separating it into spatial and temporal components. When applied to the Robertson–Walker metric, it simplifies the analysis of cosmological evolution by dividing the Einstein field equations into constraint and evolution equations. It introduces the lapse function N and the shift vector Ni, which control how time and spatial
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A nested sequence of inequivalent Rindler vacua : universal relic thermality of Planckian origin Classical Quant. Grav. (IF 3.6) Pub Date : 2025-01-06 Kinjalk Lochan, T Padmanabhan
The Bogoliubov transformation connecting the standard inertial frame mode functions to the standard mode functions defined in the Rindler frame R0, leads to the result that the inertial vacuum appears as a thermal state with temperature T0=a0/2π where a0 is the acceleration parameter of R0. We construct an infinite family of nested Rindler-like coordinate systems R1,R2,… within the right Rindler wedge
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Relativistic elastic membranes: rotating disks and Dyson spheres Classical Quant. Grav. (IF 3.6) Pub Date : 2024-12-31 Paulo Mourão, José Natário, Rodrigo Vicente
We derive the equations of motion for relativistic elastic membranes, that is, two-dimensional elastic bodies whose internal energy depends only on their stretching, starting from a variational principle. We show how to obtain conserved quantities for the membrane’s motion in the presence of spacetime symmetries, determine the membrane’s longitudinal and transverse speeds of sound in isotropic states
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Dynamical systems analysis of a cosmological model with interacting Umami Chaplygin fluid in adiabatic particle creation mechanism: some bouncing features Classical Quant. Grav. (IF 3.6) Pub Date : 2024-12-31 Goutam Mandal, Sujay Kr Biswas
The present work aims to investigate an interacting Umami Chaplygin gas (UCG) in the background dynamics of a spatially flat Friedmann–Lemaitre–Robertson–Walker Universe when adiabatic particle creation is allowed. Here, the Universe is taken to be an open thermodynamical model where the particle is created irreversibly and consequently, the creation pressure comes into the energy-momentum tensor of
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Exact regular black hole solutions with de Sitter cores and Hagedorn fluid Classical Quant. Grav. (IF 3.6) Pub Date : 2024-12-31 Vitalii Vertogradov, Ali Övgün
In this paper, we present three exact solutions to the Einstein field equations, each illustrating different black hole models. The first solution introduces a black hole with a variable equation of state, P=k(r)ρ, which can represent both singular and regular black holes depending on the parameters M0 and w0. The second solution features a black hole with Hagedorn fluid, relevant to the late stages
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Entropy production due to spacetime fluctuations Classical Quant. Grav. (IF 3.6) Pub Date : 2024-12-31 Thiago H Moreira, Lucas C Céleri
Understanding the quantum nature of the gravitational field is undoubtedly one of the greatest challenges in theoretical physics. Despite significant progress, a complete and consistent theory remains elusive. However, in the weak field approximation—where curvature effects are small—we can explore some expected properties of such a theory. Particularly relevant to this study is the quantum nature
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Host galaxy demographics of individually detectable supermassive black-hole binaries with pulsar timing arrays Classical Quant. Grav. (IF 3.6) Pub Date : 2024-12-30 Katharine Cella, Stephen R Taylor, Luke Zoltan Kelley
Massive black hole binaries (MBHBs) produce gravitational waves (GWs) that are detectable with pulsar timing arrays. We determine the properties of the host galaxies of simulated MBHBs at the time they are producing detectable GW signals. The population of MBHB systems we evaluate is from the Illustris cosmological simulations taken in tandem with post processing semi-analytic models of environmental
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Novel topological phenomena of timelike circular orbits for charged test particles Classical Quant. Grav. (IF 3.6) Pub Date : 2024-12-30 Xu Ye, Shao-Wen Wei
The topological approach has recently been successfully employed to investigate timelike circular orbits (TCOs) for massive neutral test particles. The observed vanishing topological number implies that these TCOs occur in pairs. However, the behavior of charged test particles in this regard remains unexplored. To address this issue, our study focuses on examining the influence of particle charge on