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  • Rigidity results of free boundary maximal hypersurfaces in the region bounded by a de Sitter space
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-16
    Sangwoo Park and Juncheol Pyo

    This paper provides the rigidity results of free boundary maximal hypersurfaces in a region bounded by a de Sitter space in the Lorentz–Minkowski space. First, it is proved that any smooth, compact free boundary maximal hypersurface in a de Sitter ball is the spacelike coordinate planar disk passing through the center of the de Sitter space. Second, a smooth, noncompact, complete free boundary maximal

    更新日期:2020-10-19
  • Quantum effects across dynamical horizons
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-16
    Cecilia Giavoni and Marc Schneider

    We present a generalization of the Hawking effect for dynamical trapping horizons by calculating the tunneling rate in the Hamilton–Jacobi formalism. It turns out that all horizons classified by Hayward are subjected to thermal quantum effects. While the Hawking effect for future outer and past inner trapping horizons is given as a particle emission, we show that the Hawking effect for future inner

    更新日期:2020-10-19
  • Superconformal indices at large N and the entropy of AdS 5 × SE 5 black holes
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-16
    Francesco Benini, Edoardo Colombo, Saman Soltani, Alberto Zaffaroni and Ziruo Zhang

    The large N limit of the four-dimensional superconformal index was computed and successfully compared to the entropy of a class of AdS 5 black holes only in the particular case of equal angular momenta. Using the Bethe ansatz formulation, we compute the index at large N with arbitrary chemical potentials for all charges and angular momenta, for general ##IMG## [http://ej.iop.org/images/0264-9381/3

    更新日期:2020-10-19
  • Lee-Wald charge and asymptotic behaviors of the Weyl-invariant topologically massive gravity
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-16
    Suat Dengiz, Ercan Kilicarslan and M Reza Setare

    We apply the Lee–Wald covariant phase space method to the Weyl-invariant topologically massive gravity and compute the corresponding on-shell conserved charges. By using appropriate decay conditions for the existing propagating modes in the near-horizon of a stationary black hole, we obtain the charges generating the asymptotic symmetries. We show that the charges are integrable and the (modified)

    更新日期:2020-10-19
  • Quasi-normal mode of a regular Schwarzschild black hole
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-16
    Mattia Villani

    Some quantum gravity theories, like loop quantum gravity, predict that quantum mechanical effects will avoid the formation of a singularity inside a black hole. From the general relativity point of view, this means that the metric will differ from the ones of Schwarzschild or Kerr at least inside the event horizon. If the metric is not that of Schwarzschild or Kerr, the potential of the Regge–Wheeler

    更新日期:2020-10-19
  • Advanced LIGO squeezer platform for backscattered light and optical loss reduction
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-14
    Álvaro Fernández-Galiana, Lee McCuller, Jeff Kissel, Lisa Barsotti, John Miller, Maggie Tse, Matthew Evans, Stuart M Aston, Richard Abbott, Thomas J Shaffer, Arnaud Pele, Janeen H Romie, Betsy Weaver, Peter Fritschel, Nergis Mavalvala and Fabrice Matichard

    The Advanced LIGO gravitational-wave detectors are limited by optical quantum noise in most of their detection band. To overcome this limit, squeezed vacuum states have been injected into the Advanced LIGO detectors during the third observing run (O3), leading to an increase of their detection rate by about 40% to 50%. Here we present a key element of LIGO’s squeezed vacuum source: the seismic isolation

    更新日期:2020-10-16
  • The Hawking energy on the past lightcone in cosmology
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-09
    Dennis Stock

    This work studies the Hawking energy in a cosmological context. The past lightcone of a point in spacetime is the natural geometric structure closely linked to cosmological observations. By slicing the past lightcone into a one-parameter family of spacelike two-surfaces, the evolution of the Hawking energy down the lightcone is studied. Strong gravitational fields may generate lightcone self-intersections

    更新日期:2020-10-12
  • 3 m × 3 m heterolithic passive resonant gyroscope with cavity length stabilization
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-09
    Fenglei Zhang, Kui Liu, Zongyang Li, Xiaohua Feng, Ke Li, Yanxia Ye, Yunlong Sun, Leilei He, K Ulrich Schreiber, Jun Luo, Zehuang Lu and Jie Zhang

    Large-scale high sensitivity laser gyroscopes have important applications for ground-based and space-based gravitational wave detection. We report on the development of a 3 m × 3 m heterolithic passive resonant gyroscope (HUST-1) which is installed on the ground of a cave laboratory. We operate the HUST-1 on different longitudinal cavity modes and the rotation sensitivity reaches 1.6 × 10 −9 rad s

    更新日期:2020-10-12
  • The mass quadrupole moment of compact binary systems at the fourth post-Newtonian order
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-08
    Tanguy Marchand, Quentin Henry, François Larrouturou, Sylvain Marsat, Guillaume Faye and Luc Blanchet

    The mass-type quadrupole moment of inspiralling compact binaries (without spins) is computed at the fourth post-Newtonian (4PN) approximation of general relativity. The multipole moments are defined by matching between the field in the exterior zone of the matter system and the PN field in the near zone, following the multipolar-post-Minkowskian (MPM)-PN formalism. The matching implies a specific regularization

    更新日期:2020-10-12
  • The missing link in gravitational-wave astronomy: discoveries waiting in the decihertz range
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-07
    Manuel Arca Sedda, Christopher P L Berry, Karan Jani, Pau Amaro-Seoane, Pierre Auclair, Jonathon Baird, Tessa Baker, Emanuele Berti, Katelyn Breivik, Adam Burrows, Chiara Caprini, Xian Chen, Daniela Doneva, Jose M Ezquiaga, K E Saavik Ford, Michael L Katz, Shimon Kolkowitz, Barry McKernan, Guido Mueller, Germano Nardini, Igor Pikovski, Surjeet Rajendran, Alberto Sesana, Lijing Shao, Nicola Tamanini

    The gravitational-wave astronomical revolution began in 2015 with LIGO’s observation of the coalescence of two stellar-mass black holes. Over the coming decades, ground-based detectors like laser interferometer gravitational-wave observatory (LIGO), Virgo and KAGRA will extend their reach, discovering thousands of stellar-mass binaries. In the 2030s, the space-based laser interferometer space antenna

    更新日期:2020-10-08
  • Chemistry and complexity for solitons in AdS 5
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-06
    Shane Andrews, Robie A Hennigar and Hari K Kunduri

    Minimal D = 5 supergravity admits asymptotically globally AdS 5 gravitational solitons (stationary, geodesically complete, horizonless spacetimes with positive mass). We show that, like asymptotically flat gravitational solitons, these solutions satisfy mass and mass variation formulas analogous to those satisfied by AdS black holes. A thermodynamic volume associated to the non-trivial topology of

    更新日期:2020-10-07
  • Deflection angle and shadow behaviors of quintessential black holes in arbitrary dimensions
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-06
    A Belhaj, M Benali, A El Balali, H El Moumni and S-E Ennadifi

    Motivated by M-theory/superstring inspired models, we investigate certain behaviors of the deflection angle and the shadow geometrical shapes of higher dimensional quintessential black holes associated with two values of the dark energy (DE) state parameter, being ##IMG## [http://ej.iop.org/images/0264-9381/37/21/215004/cqgabbaa9ieqn1.gif] {$\omega =-\frac{1}{3}$} and ##IMG## [http://ej.iop.org/im

    更新日期:2020-10-07
  • Probing string-inspired gravity with the inspiral–merger–ringdown consistency tests of gravitational waves
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-06
    Zack Carson and Kent Yagi

    The extreme-gravity collisions between black holes allow us to probe the underlying theory of gravity. We apply a predictive forecast of the theory-agnostic inspiral–merger–ringdown consistency test to an example theory beyond general relativity for the first time, for future gravitational wave observations. Here we focus on the string-inspired Einstein-dilaton Gauss–Bonnet gravity and modify the inspiral

    更新日期:2020-10-07
  • Quasi-probability distributions in loop quantum cosmology
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-06
    Jasel Berra-Montiel and Alberto Molgado

    In this paper, we introduce a complete family of parametrized quasi-probability distributions in phase space and their corresponding Weyl quantization maps with the aim to generalize the recently developed Wigner–Weyl formalism within the loop quantum cosmology (LQC) program. In particular, we intend to define those quasi-distributions for states valued on the Bohr compactification of the real line

    更新日期:2020-10-07
  • Non-aligned Einstein–Maxwell Robinson–Trautman fields of Petrov type D
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-06
    Norbert Van den Bergh and John Carminati

    We discuss Petrov type D Einstein–Maxwell (EM) fields in which both double null eigenvectors of the Weyl tensor are non-aligned with the eigenvectors of a non-null electromagnetic field and are assumed to be geodesic, shear-free, diverging and non-twisting. We obtain the general solution of the EM equations under the extra condition that the complex null vectors of the Weyl canonical tetrad are hypersurface

    更新日期:2020-10-07
  • Josephson AC effect induced by weak gravitational field
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-05
    Giovanni Alberto Ummarino and Antonio Gallerati

    In this paper we examine the possibility of a Josephson AC effect between two superconductors induced by the Earth’s gravitational field, making use of the gravito-Maxwell formalism. The theoretical framework exploits the symmetry between the weak field expansion of the gravitational field and the standard Maxwell formulation, combined with the Josephson junction physics. We also suggest a suitable

    更新日期:2020-10-06
  • Probing the era of reheating for reconstructed inflationary potential in the RS II braneworld
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-05
    Sukannya Bhattacharya, Kumar Das and Mayukh R Gangopadhyay

    We analyse the epoch of reheating after an inflationary phase in the Randall–Sundrum type-II braneworld, where we did not consider any particular model of inflation, but rather reconstructed the inflationary potential solving the flow equations using Monte Carlo (MC) approach. It is shown numerically that a potential conceived through the MC reconstruction technique can be represented by an effective

    更新日期:2020-10-06
  • Junction conditions in Palatini f ( R ) gravity
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-05
    Gonzalo J Olmo and Diego Rubiera-Garcia

    We work out the junction conditions for f ( R ) gravity formulated in metric-affine (Palatini) spaces using a tensor distributional approach. These conditions are needed for building consistent models of gravitating bodies with an interior and exterior regions matched at some hypersurface. Some of these conditions depart from the standard Darmois-Israel ones of general relativity and from their metric

    更新日期:2020-10-06
  • The cosmological constant from conformal transformations: Möbius invariance and Schwarzian action
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-01
    Jibril Ben Achour and Etera R Livine

    The homogeneous Friedman–Lemaî tre-Robertson–Walker (FLRW) cosmology of a free scalar field with vanishing cosmological constant was recently shown to be invariant under the one-dimensional conformal group ##IMG## [http://ej.iop.org/images/0264-9381/37/21/215001/cqgabb577ieqn5.gif] {$\mathrm{S}\mathrm{L}\left(2,\mathbb{R}\right)$} acting as Möbius transformations on the proper time. Here we generalize

    更新日期:2020-10-02
  • Harmonic coordinates of the Kerr metric revisited
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-10-01
    Yunlong Zang, Xiaokai He and Zhoujian Cao

    Starting from the Kerr–Schild coordinates, a set of horizon penetrating harmonic coordinates for the Kerr metric is worked out and exhibit the explicit form of the whole metric. As a validity check on the calculations, the multipole expansion of the Kerr metric is then derived from the harmonic formulation. The resemblance of the geometry of the harmonic slicing with the ‘1 + log’ slicing and the generalized

    更新日期:2020-10-02
  • An examination of geometrical and potential time delays in gravitational lensing
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-29
    Oleg Yu Tsupko, Gennady S Bisnovatyi-Kogan, Adam Rogers and Xinzhong Er

    In this paper we investigate the relation between the potential and geometric time delays in gravitational lensing. In the original paper of Shapiro (1964), it is stated that there is a time delay in the radar signals between Earth and Venus that pass near a massive object (the Sun), compared to the path taken in the absence of any mass. The reason for this delay is connected with the influence of

    更新日期:2020-09-30
  • Testing the Kerr nature of supermassive and intermediate-mass black hole binaries using spin-induced multipole moment measurements
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-29
    N V Krishnendu and Anjali B Yelikar

    The gravitational wave measurements of spin-induced multipole moment coefficients of a binary black hole system can be used to distinguish black holes from other compact objects [1]. Here, we apply the idea proposed in reference [1] to binary systems composed of supermassive and intermediate-mass black holes and derive the expected bounds on their Kerr nature using future space-based gravitational

    更新日期:2020-09-30
  • Demonstration of dynamic thermal compensation for parametric instability suppression in Advanced LIGO
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-29
    T Hardwick, V J Hamedan, C Blair, A C Green and D Vander-Hyde

    Advanced LIGO and other ground-based interferometric gravitational-wave detectors use high laser power to minimize shot noise and suspended optics to reduce seismic noise coupling. This can result in an opto-mechanical coupling which can become unstable and saturate the interferometer control systems. The severity of these parametric instabilities scales with circulating laser power and first hindered

    更新日期:2020-09-30
  • Note on equatorial geodesics in circular spacetimes
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-29
    K Van Aelst

    General results on equatorial geodesics are exposed in the case of circular spacetimes featuring an equatorial reflection symmetry. The way the geodesic equation equivalently rewrites in terms of an effective potential is explicitly recalled for circular and non-circular equatorial geodesics. This provides a practical tool to discuss their stability. Statements are illustrated in Kerr spacetime.

    更新日期:2020-09-30
  • Singularity resolution depends on the clock
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-29
    Steffen Gielen and Lucía Menéndez-Pidal

    We study the quantum cosmology of a flat Friedmann–Lemaître–Robertson–Walker Universe filled with a (free) massless scalar field and a perfect fluid that represents radiation or a cosmological constant whose value is not fixed by the action, as in unimodular gravity. We study two versions of the quantum theory: the first is based on a time coordinate conjugate to the radiation/dark energy matter component

    更新日期:2020-09-30
  • Effective equation of state in modified gravity and observational constraints
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-29
    Simran Arora, Xin-he Meng, S K J Pacif and P K Sahoo

    In this article, the bulk viscosity is introduced in a modified gravity model. The gravitational action has a general f ( R , T ) form, where R and T are the curvature scalar and the trace of energy momentum tensor respectively. An effective equation of state (EoS) has been investigated in the cosmological evolution with bulk viscosity. In the present scenario, the Hubble parameter which has a scaling

    更新日期:2020-09-30
  • Self-gravitating razor-thin discs around black holes via multi-hole seeds
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-25
    Ronaldo S S Vieira

    We construct self-gravitating razor-thin discs of counterrotating matter around Schwarzschild black holes (BHs) by applying the ‘displace, cut, and reflect’ method to known seed solutions representing multi-holes. All but one of the sources of the seed solution generate the surrounding annular disc, whereas the remaining BH is mapped onto a Schwarzschild BH which lies at the disc centre after the transformation

    更新日期:2020-09-26
  • Critical heat engines in massive gravity
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-25
    Pavan Kumar Yerra and Chandrasekhar Bhamidipati

    With in the extended thermodynamics, we study the efficiency η k of critical heat engines for charged black holes in massive gravity for spherical ( k = 1), flat ( k = 0) and hyperbolic ( k = −1) topologies. Although, η k is in general higher (lower) for hyperbolic (spherical) topology, we show that this order can be reversed in critical heat engines with efficiency higher for spherical topology, following

    更新日期:2020-09-26
  • Coherent gravitational waveforms and memory from cosmic string loops
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-24
    Josu C Aurrekoetxea, Thomas Helfer and Eugene A Lim

    We construct, for the first time, the time-domain gravitational wave strain waveform from the collapse of a strongly gravitating Abelian Higgs cosmic string loop in full general relativity. We show that the strain exhibits a large memory effect during merger, ending with a burst and the characteristic ringdown as a black hole is formed. Furthermore, we investigate the waveform and energy emitted as

    更新日期:2020-09-25
  • Lagrangian density and local symmetries of inhomogeneous hyperconical universes
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-24
    Robert Monjo and Rutwig Campoamor-Stursberg

    Hyperconical universes can be represented by means of an inhomogeneous metric with positive curvature and linear expansion, that is isomorphic to flat universes with acceleration thanks to an appropriate transformation. Various symmetry properties of this metric are analysed, primarily at the local scale. In particular, the Lagrangian formalism and the Arnowitt–Deser–Misner (ADM) equations are applied

    更新日期:2020-09-25
  • First law of black hole mechanics with fermions
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-23
    P B Aneesh, Sumanta Chakraborty, Sk Jahanur Hoque and Amitabh Virmani

    In the last few years, there has been significant interest in understanding the stationary comparison version of the first law of black hole mechanics in the vielbein formulation of gravity. Several authors have pointed out that to discuss the first law in the vielbein formulation one must extend the Iyer–Wald Noether charge formalism appropriately. Jacobson and Mohd (2015 Phys. Rev. D 92 124010) and

    更新日期:2020-09-24
  • Quantum geometry from higher gauge theory
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-23
    Seth K Asante, Bianca Dittrich, Florian Girelli, Aldo Riello and Panagiotis Tsimiklis

    Higher gauge theories play a prominent role in the construction of 4D topological invariants and have been long ago proposed as a tool for 4D quantum gravity. The Yetter lattice model and its continuum counterpart, the BFCG theory, generalize BF theory to 2-gauge groups and—when specialized to 4D and the Poincaré 2-group—they provide an exactly solvable topologically-flat version of 4D general relativity

    更新日期:2020-09-24
  • Double field inflation of generalized dilaton–axion models with a new Fayet–Iliopoulos (FI) term
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-23
    MAN Ping Kwan Ellgan

    We study the inflation dynamics of generalized dilaton–axion models with a new Fayet–Iliopoulos (FI) term, where both real and imaginary parts of the ‘dilaton–axion’ super-field evolve. We find that the turn rate per Hubble parameter is about ##IMG## [http://ej.iop.org/images/0264-9381/37/20/205016/cqgab9bbcieqn6.gif] {$O\left({10}^{-2}\right)$} to ##IMG## [http://ej.iop.org/images/0264-9381/37/20

    更新日期:2020-09-24
  • Reversible dynamics with closed time-like curves and freedom of choice
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-21
    Germain Tobar and Fabio Costa

    The theory of general relativity predicts the existence of closed time-like curves (CTCs), which theoretically would allow an observer to travel back in time and interact with their past self. This raises the question of whether this could create a grandfather paradox, in which the observer interacts in such a way to prevent their own time travel. Previous research has proposed a framework for deterministic

    更新日期:2020-09-22
  • Particle swarming of sensor correction filters
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-21
    Jonathan J Carter, Samuel J Cooper, Edward Thrift, Joseph Briggs, Jim Warner, Michael P Ross and Conor M Mow-Lowry

    Reducing the impact of seismic activity on the motion of suspended optics is essential for the operation of ground-based gravitational wave detectors. During periods of increased seismic activity, low-frequency ground translation and tilt cause the Advanced LIGO observatories to lose ‘lock’, reducing their duty cycles. This paper applies modern global-optimisation algorithms to aid in the design of

    更新日期:2020-09-22
  • Cosmological dark matter amplification through dark torsion
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-21
    Fernando Izaurieta and Samuel Lepe

    A cosmological approach based on considering a cosmic background with non-zero torsion is shown in order to give an option of explaining a possible phantom evolution, not ruled out according to the current observational data. We revise some aspects of the formal schemes on torsion and, according them, we develop a formalism which can be an interesting alternative for exploring Cosmology.

    更新日期:2020-09-22
  • Kinematical and dynamical aspects of ghost-matter cosmologies
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-21
    Ameya Chavda, John D Barrow and Christos G Tsagas

    We consider the kinematical and dynamical evolution of Friedmann Universes with a mixture of non-interacting matter and a ghost-like field, in a scenario analogous to that advocated by the Quintom model. Assuming that the conventional matter dominates today, we find that the ghost component can bring the future expansion and the past contraction of the model to a finite halt. Moreover, at the moment

    更新日期:2020-09-22
  • Thermodynamic instabilities in holographic neutron stars at finite temperature
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-21
    Carlos R Argüelles, Tobías Canavesi, Manuel Díaz and Nicolás Grandi

    We study the thermodynamics of a self-gravitating system of neutral fermions at finite temperature and analyze its backreaction in an asymptotically AdS space. We evaluate numerically the free entropy as a function of temperature, and perform a stability analysis applying the simpler and powerful graphical method referred as the Katz criterion. We found that for highly-enough degenerate fermionic solutions

    更新日期:2020-09-22
  • Hopf link volume simplicity constraints in spin foam models
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-21
    Mehdi Assanioussi and Benjamin Bahr

    In this article we consider specific bivector geometries which arise in the large-spin limit of the extension of the Engle–Pereira–Rovelli–Livine spin foam model for quantum gravity by Kaminski, Kisielowski and Lewandowski. We address the implementation of volume simplicity constraints, which are required to ensure that a 4 d metric can be reconstructed from the bivector geometry. We find that the

    更新日期:2020-09-22
  • Can we use next-generation gravitational wave detectors for terrestrial precision measurements of Shapiro delay?
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-21
    Andrew G Sullivan, Doğa Veske, Zsuzsa Márka, Imre Bartos, Stefan Ballmer, Peter Shawhan and Szabolcs Márka

    Shapiro time delay is one of the fundamental tests of general relativity and post-Newtonian theories of gravity. Consequently, its measurements can be used to probe the parameter γ which is related to spacetime curvature produced by a unit mass in the post-Newtonian formalism of gravity. To date all measurements of time delay have been conducted on astronomical scales. It was asserted in 2010 that

    更新日期:2020-09-22
  • Influence of the residual gas damping noise in the test of the gravitational inverse-square law
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-21
    Jun Ke, Jie Luo, Yu-Jie Tan and Cheng-Gang Shao

    Many theories, such as the unification theories that would include gravitation, predict deviations from Newtonian inverse-square law (ISL) at short range. Many high precision experiments have been performed, but additional experiments are still of high scientific importance. Here, we discuss the torque thermal noise caused by residual gas damping, especially the effect of squeeze-film damping, in a

    更新日期:2020-09-22
  • Spherically symmetric loop quantum gravity: analysis of improved dynamics
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-21
    Rodolfo Gambini, Javier Olmedo and Jorge Pullin

    We study the ‘improved dynamics’ for the treatment of spherically symmetric space-times in loop quantum gravity introduced by Chiou et al in analogy with the one that has been constructed by Ashtekar, Pawlowski and Singh for the homogeneous space-times. In this dynamics the polymerization parameter is a well motivated function of the dynamical variables, reflecting the fact that the quantum of area

    更新日期:2020-09-22
  • Non-singular Kerr-NUT-de Sitter spacetimes
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-21
    Jerzy Lewandowski and Maciej Ossowski

    We study Killing horizons and their neighbourhoods in the Kerr–NUT–(anti-)de Sitter and the accelerated Kerr–NUT–(anti-)de Sitter spacetimes. The geometries of the horizons have an irremovable singularity at one of the poles, unless the parameters characterising the spacetimes satisfy the constraint we derive and solve in the current paper. In the Kerr-NUT-de Sitter case, the constraint relates the

    更新日期:2020-09-22
  • Searching for MHz gravitational waves from harmonic sources
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-21
    Jeronimo G. C. Martinez and Brittany Kamai

    A MHz gravitational wave search for harmonic sources was conducted using a 704 h dataset obtained from the Holometer, a pair of 40 m power recycled Michelson interferometers. Our search was designed to look for cosmic string loops and eccentric black hole binaries in an entirely unexplored frequency range from 1 to 25 MHz. The measured cross-spectral density between both interferometers was used to

    更新日期:2020-09-22
  • On the power-law Maxwell nonlinear electrodynamics
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-18
    S Habib Mazharimousavi

    We re-examine the power-law Maxwell nonlinear electrodynamics (NED) where the generalized Maxwell’s Lagrangian is considered to be ##IMG## [http://ej.iop.org/images/0264-9381/37/19/197001/cqgabb07bieqn1.gif] {$-\alpha {\left\vert {F}_{\alpha \beta }{F}^{\alpha \beta }\right\vert }^{s}$} . In [1], where a d -dimensional static spherically symmetric spacetime was considered the pure electric field has

    更新日期:2020-09-20
  • A SO(1,3) gauge theory of quantum gravity: quantization and renormalizability proof
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-18
    C Wiesendanger

    A new SO(1,3) gauge field theory classically equivalent to general relativity in a limiting case is quantized and the gauge-fixed path integral representation of the quantum effective action (QEA) is derived. Both the gauge-fixed classical action and the QEA are shown to be invariant under nilpotent BRST variations of the gauge, matter, ghost, antighost and Nakanishi–Lautrup fields defining the theory

    更新日期:2020-09-20
  • Energy conditions in general relativity and quantum field theory
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-18
    Eleni-Alexandra Kontou and Ko Sanders

    This review summarizes the current status of the energy conditions in general relativity and quantum field theory. We provide a historical review and a summary of technical results and applications, complemented with a few new derivations and discussions. We pay special attention to the role of the equations of motion and to the relation between classical and quantum theories. Pointwise energy conditions

    更新日期:2020-09-20
  • Axis potentials for stationary n -black-hole configurations
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-17
    Jörg Hennig

    We extend earlier discussions of the balance problem for two black holes and study stationary spacetimes containing an arbitrary number of n aligned rotating and (possibly) charged black holes. For these hypothetical equilibrium configurations, we obtain the most general form of the boundary data on the symmetry axis in terms of a finite number of parameters. Hence future investigations of n -black-hole

    更新日期:2020-09-20
  • Horseshoes and invariant tori in cosmological models with a coupled field and non-zero curvature
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-17
    Leo T Butler

    This paper studies the dynamics of a family of Hamiltonian systems that originate from Friedman–Lemaître–Robertson–Walker space-times with a coupled field and non-zero curvature. In four distinct cases, previously considered by Maciejewski, Przybylska, Stachowiak and Szydowski, it is shown that there are homoclinic connections to invariant submanifolds and the connections split. These results imply

    更新日期:2020-09-20
  • Revisiting pre-inflationary Universe of family of α -attractor in loop quantum cosmology
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-16
    M Shahalam, Mudhahir Al Ajmi, R Myrzakulov and Anzhong Wang

    In this work, we revisit the dynamics of pre-inflationary Universe with a family of α -attractor potentials, in the framework of loop quantum cosmology, in which the big bang singularity is generically resolved purely with quantum geometric effects, and replaced by a quantum bounce. At the bounce, the background evolution is divided into two distinct classes, the first is dominated by the kinetic energy

    更新日期:2020-09-18
  • Embedded BHs and multipole globules: clustered misaligned thick accretion disks around static SMBHs
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-15
    D Pugliese and Z Stuchlík

    We investigate clusters of misaligned (inclined) tori orbiting a central static Schwarzschild black hole. To this purpose we considered a set of geometrically thick, pressure supported, perfect fluid tori analyzing purely hydrodynamic models. We study the tori collision emergence and, consequently, the stability properties of the aggregates composed by tori with different inclination angles relative

    更新日期:2020-09-16
  • Brane-worlds and the Calabi–Yau complex structure moduli
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-15
    Moataz H Emam, H H Salah and Safinaz Salem

    In this paper we extend previous work on the relation between the complex structure moduli of the underlying Calabi–Yau manifold in five dimensional supergravity with the time evolution of an embedded 3-brane. We numerically solve the fields’ equations for such a construction and focus on dust and radiation filled branes; with the possible application of modeling the Universe as a brane-world. It is

    更新日期:2020-09-16
  • Stability for small data: the drift model of the conformal method
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-15
    Caterina Vâlcu

    The conformal method in general relativity aims at successfully parametrising the set of all initial data associated with globally hyperbolic spacetimes. One such mapping was suggested by Maxwell D (2014 Initial data in general relativity described by expansion, conformal deformation and drift (arXiv:1407.1467)). For closed manifolds, I verify that the solutions of the corresponding conformal system

    更新日期:2020-09-16
  • A criterion for covariance in complex sequential growth models
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-15
    Sumati Surya and Stav Zalel

    The classical sequential growth model for causal sets provides a template for the dynamics in the deep quantum regime. This growth dynamics is intrinsically temporal and causal, with each new element being added to the existing causal set without disturbing its past. In the quantum version, the probability measure on the event algebra is replaced by a quantum measure, which is Hilbert space valued

    更新日期:2020-09-16
  • Phase space mixing in an external gravitational central potential
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-15
    Paola Rioseco and Olivier Sarbach

    This article is devoted to the study of the dynamical behavior of a collisionless kinetic gas in d = 1, 2, 3 space dimensions which is trapped in a rotationally symmetric potential well. Although at the microscopic level the trajectories of individual gas particles are quasi-periodic and characterized by their d fundamental frequencies, at the macroscopic level the gas relaxes in time to a stationary

    更新日期:2020-09-16
  • Where is Love? Tidal deformability in the black hole compactness limit
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-11
    Cecilia Chirenti, Camilo Posada and Victor Guedes

    One of the macroscopically measurable effects of gravity is the tidal deformability of astrophysical objects, which can be quantified by their tidal Love numbers. For planets and stars, these numbers measure the resistance of their material against the tidal forces, and the resulting contribution to their gravitational multipole moments. According to general relativity, nonrotating deformed black holes

    更新日期:2020-09-12
  • Lorentzian Snyder spacetimes and their Galilei and Carroll limits from projective geometry
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-11
    Angel Ballesteros, Giulia Gubitosi and Francisco J Herranz

    We show that the Lorentzian Snyder models, together with their Galilei and Carroll limiting cases, can be rigorously constructed through the projective geometry description of Lorentzian, Galilean and Carrollian spaces with nonvanishing constant curvature. The projective coordinates of such curved spaces take the role of momenta, while translation generators over the same spaces are identified with

    更新日期:2020-09-12
  • Machine learning for gravitational-wave detection: surrogate Wiener filtering for the prediction and optimized cancellation of Newtonian noise at Virgo
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-11
    F Badaracco, J Harms, A Bertolini, T Bulik, I Fiori, B Idzkowski, A Kutynia, K Nikliborc, F Paoletti, A Paoli, L Rei and M Suchinski

    The cancellation of noise from terrestrial gravity fluctuations, also known as Newtonian noise (NN), in gravitational-wave detectors is a formidable challenge. Gravity fluctuations result from density perturbations associated with environmental fields, e.g., seismic and acoustic fields, which are characterized by complex spatial correlations. Measurements of these fields necessarily provide incomplete

    更新日期:2020-09-12
  • Parisi-Sourlas supergravity
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-11
    Matthew Kellett and Tim R Morris

    A manifestly diffeomorphism invariant exact renormalization group requires extra diffeomorphism invariant ultraviolet regularisation at some effective cutoff scale Λ. This motivates construction of a ‘Parisi-Sourlas’ supergravity, in analogy with the gauge theory case, where the superpartner fields have the wrong spin-statistics such that they can become Pauli–Villars regulator fields after spontaneous

    更新日期:2020-09-12
  • The coupling of matter and spacetime geometry
    Classical Quant. Grav. (IF 3.071) Pub Date : 2020-09-11
    Jose Beltrán Jiménez, Lavinia Heisenberg and Tomi Koivisto

    The geometrical formulation of gravity is not unique and can be set up in a variety of spacetimes. Even though the gravitational sector enjoys this freedom of different geometrical interpretations, consistent matter couplings have to be assured for a steady foundation of gravity. In generalised geometries, further ambiguities arise in the matter couplings unless the minimal coupling principle (MCP)

    更新日期:2020-09-12
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