CLASSICAL AND QUANTUM GRAVITY 是引力和时空理论领域的物理学家、数学家和宇宙学家的知名期刊。该杂志现在是公认的经典相对论和量子引力所有领域的世界领导者。

Classical and Quantum Gravity is a renowned journal in the field of gravity and spacetime theory, widely recognized by physicists, mathematicians, and cosmologists. The journal is acknowledged as a world leader in all areas of classical relativity and quantum gravity.

《Classical and Quantum Gravity》是引力和时空理论领域的知名期刊，受到物理学家、数学家和宇宙学家的广泛认可。该杂志被公认为经典相对论和量子引力各个领域的全球领导者。

Classical and Quantum Gravity

Abstract Without specifying a matter field nor imposing energy conditions, we study Killing horizons in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>n</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mtext>⩾</mml:mtext> <mml:mn>3</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> -dimensional static solutions in general relativity with an <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mi>n</mml:mi> <mml:mo>−</mml:mo> <mml:mn>2</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> -dimensional Einstein base manifold. Assuming linear relations <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>p</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> <mml:mo>≃</mml:mo> <mml:msub> <mml:mi>χ</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> <mml:mi>ρ</mml:mi> </mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>p</mml:mi> <mml:mn>2</mml:mn> </mml:msub> <mml:mo>≃</mml:mo> <mml:msub> <mml:mi>χ</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">t</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> <mml:mi>ρ</mml:mi> </mml:mrow> </mml:math> near a Killing horizon between the energy density ρ , radial pressure <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>p</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> , and tangential pressure p 2 of the matter field, we prove that any non-vacuum solution satisfying <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>χ</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> <mml:mo>&lt;</mml:mo> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:math> ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>χ</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> <mml:mo>≠</mml:mo> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:math> ) or <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>χ</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> <mml:mo>&gt;</mml:mo> <mml:mn>0</mml:mn> </mml:mrow> </mml:math> does not admit a horizon as it becomes a curvature singularity. For <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>χ</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>χ</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> <mml:mo>∈</mml:mo> <mml:mo stretchy="false">[</mml:mo> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mn>3</mml:mn> <mml:mo>,</mml:mo> <mml:mn>0</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> , non-vacuum solutions admit Killing horizons, on which there exists a matter field only for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>χ</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:math> , which are of the Hawking–Ellis type I and type II, respectively. Differentiability of the metric on the horizon depends on the value of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>χ</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> , and non-analytic extensions beyond the horizon are allowed for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>χ</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> <mml:mo>∈</mml:mo> <mml:mo stretchy="false">[</mml:mo> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mn>3</mml:mn> <mml:mo>,</mml:mo> <mml:mn>0</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> . In particular, solutions can be attached to the Schwarzschild–Tangherlini-type vacuum solution at the Killing horizon in at least a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msup> <mml:mi>C</mml:mi> <mml:mrow> <mml:mn>1</mml:mn> <mml:mo>,</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> regular manner without a lightlike thin shell. We generalize some of those results in Lovelock gravity with a maximally symmetric base manifold.

Hideki Maeda

Cristián Martínez

Existence and absence of Killing horizons in static solutions with symmetries

静态对称解中Killing视界的存与缺

The Gravity Probe B (GP-B) satellite used electrostatically suspended gyroscopes to test two predictions of general relativity. Here, we describe the satellite's proportional thrusters, which utilized boil-off helium gas for attitude and translation Control (ATC). The evolution of the design and its successful effect on orbit performance is reported.

D DeBra

W J Bencze

C W F Everitt

J VandenBeukel

J Kirschenbaum

Class. Quantum Grav.

Proportional helium thrusters for Gravity Probe B

重力探测器B的比例氦推进器

We derive a formula for the black hole entropy in theories with gravitational Chern-Simons terms, by generalizing Wald's argument which uses the Noether charge. It correctly reproduces the entropy of three-dimensional black holes in the presence of Chern-Simons term, which was previously obtained via indirect methods.

Yuji Tachikawa

Black hole entropy in the presence of Chern–Simons terms

存在Chern-Simons项的黑洞熵

Abstract For the purpose of detecting gravitational waves from space, high-energy particles will infiltrate the satellite’s structure and accumulate charges on the test mass, consequently diminishing detection performance. Present investigations into the charging rate of the test mass typically rely on the particle distribution of Earth orbit. However, the influence of the Earth’s magnetosphere needs to be considered for the Tianqin detector because of its geocentric orbit. In this paper, artificial neural network is used to fuse satellite data and the galactic cosmic rays model to give the distribution of high-energy particles in the Tianqin orbit. And then, the charging rate is estimated by Monte Carlo simulation. The simulation results show that the flux of hundreds of MeV particles is a little higher than that in Earth orbit, which lead to <?CDATA $3\!-\!4$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>3</mml:mn> <mml:mo>−</mml:mo> <mml:mn>4</mml:mn> </mml:math> e s −1 higher than LISA, i.e. the charging rate of approximately 43 e s −1 during periods of solar minimum and 19 e s −1 during periods of solar maximum. These findings hold substantial implications for guiding the design of the charge management system.

Chi Lei

Wei Su

Wei Hong

Honggang Li

Menghao Zhao

Bingxue Chen

Liangyu Chu

Qingqing Li

Yanzheng Bai

Zebing Zhou

Simulation for the test mass charging rate in the Tianqin orbit

天琴轨道中测试质量充电率的仿真

Abstract TianQin is a proposed space-based gravitational-wave detector mission to be deployed and operated in high Earth orbits. As a sequel to Zhang et al (2021 Phys. Rev. D 103 062001), we investigate a type of ‘orbital noise’ in TianQin’s range acceleration that is caused by gravitational perturbation associated with solar free oscillations. Frequencies of such oscillations are typically within TianQin’s measurement band of 0.1 mHz–1 Hz, and the disturbance level needs careful assessment. By using high-precision orbit propagation and adding the Sun’s time-variable oblateness J 2 to detailed gravity-field models, we examine the effect in the frequency domain and show that the solar free oscillation noise is expected to be two orders of magnitude lower than the noise requirement on single links and hence has little impact on the mission.

Kun Liu

Chengjian Luo

Xuefeng Zhang

Effect of solar free oscillations on TianQin’s range acceleration noise

太阳自由振荡对天琴测距加速度噪声的影响

Gravitational waves cause a precession in a freely falling spinning object and a net change of orientation after the passage of the wave, dubbed as the gyroscopic memory. In this paper, we will consider isolated gravitational sources in the post-Newtonian framework and compute the gyroscopic precession and memory at leading post-Newtonian (PN) orders. We make a comparison between two competing contributions: the spin memory and the nonlinear helicity flux. At the level of the precession rate, the former is a 2PN oscillatory effect, while the latter is a 4PN adiabatic effect. However, the gyroscopic memory involves a time integration, which enhances subleading adiabatic effects by the fifth power of the velocity of light, leading to a 1.5PN memory effect. We explicitly compute the leading effects for a quasi-circular binary system and obtain the angular dependence of the memory on the celestial sphere.

Guillaume Faye

Ali Seraj

Gyroscopic Gravitational Memory from quasi-circular binary systems

准圆形双星系统的陀螺引力记忆效应

Abstract Space-based gravitational-wave detectors, such as 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 with the clock desynchronizations between emitting and receiving spacecraft. For interspacecraft clock synchronization, we need to isolate the diﬀerential clock desynchronizations, i.e., disentangle the pseudoranges. This further yields estimates for the interspacecraft light travel times, which are required as delays for the laser frequency noise suppression via time-delay interferometry. Previous studies on pseudorange disentanglement apply various simpliﬁcations in the pseudorange modeling and the data simulation. In contrast, this article derives an accurate pseudorange model in the barycentric celestial reference system, complemented by realistic state-of-the-art LISA data simulations. Concerning pseudorange disentanglement, this leads to an a priori under-determined system. We demonstrate how on-ground orbit determinations, as well as onboard transmission and on-ground reception time tags of the telemetry data, can be used to resolve this degeneracy. We introduce an algorithm for pseudorange disentanglement based on a nonstandard Kalman ﬁlter specially designed for clock synchronization in systems where pseudorange measurements are conducted in diﬀerent time frames. This algorithm achieves interspacecraft clock synchronization and light travel time estimation with submeter accuracy, thus fulﬁlling the requirements of time-delay interferometry.&amp;#xD;

Jan Niklas Reinhardt

Olaf Hartwig

Gerhard Heinzel

Clock synchronization and light-travel-time estimation for space-based gravitational-wave detectors

基于空间的引力波探测器的时钟同步与光传播时间估计

Abstract 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 $N^i$, which control how time and spatial coordinates evolve between hypersurfaces. In standard model cosmology, $N = 1$ and $N^i = 0$ for the Robertson-Walker metric. However, the $N$ becomes a function of time when we apply the metric to the minimally extended varying speed of light model. This approach allows for a more direct examination of the evolution of spatial geometry and offers flexibility in handling scenarios where the lapse function and shift vector vary. In this manuscript, we derive the model's $N$, $N^i$, along with the constraint and evolution equations, and demonstrate their consistency with the existing Einstein equations. We have shown in a previous paper that the possibility of changes in the speed of light in the Robertson-Walker metric is due to cosmological time dilation. Through the $3+1$ formalism, we can make the physical significance more explicit and demonstrate that it can be interpreted as the lapse function. From this, we show that the minimally extended varying speed of light model is consistent.

Seokcheon Lee

3+1 formalism of the minimally extended varying speed of light model

最小扩展变光速模型的3+1形式化

Abstract 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 which violate all global symmetries in the effective action for matter. Because of its central role, it is crucial to understand limitations to the validity of this conjecture.&amp;#xD;In the context of the Lorentzian path integral over spacetime geometries, we explore whether virtual black-hole configurations can be suppressed dynamically. &amp;#xD;To that end, we work in a spherically symmetric setting and make use of horizon-detecting curvature invariants which vanish on the horizon. By constructing a non-local action from the inverse of such curvature invariants, we can achieve destructive interference of black-hole configurations in the path integral.

Johanna N. Borissova

Astrid Eichhorn

Shouryya Ray

A non-local way around the no-global-symmetries conjecture in quantum gravity?

量子引力中绕过无全局对称性猜想的非局域方法？

Abstract The Bogoliubov transformation connecting the standard inertial frame mode functions to &amp;#xD; the standard mode functions defined in the Rindler frame $R_0$, leads to the result that the inertial vacuum appears as a thermal state with temperature $T_0=a_0/2\pi$ where $a_0$ is the acceleration parameter of $R_0$. We construct an infinite family of nested Rindler-like coordinate systems $R_1, R_2, ...$ within the right Rindler wedge, with time coordinates $\tau_1, \tau_2, ...,$ and acceleration parameters $a_1, a_2, ...$ by shifting the origin along the inertial $x$-axis by amounts $\ell_1, \ell_2,\cdots$. We show that, apart from the inertial vacuum, the \textit{Rindler vacuum} of the frame $R_n$ also appears to be a thermal state in the frame $R_{n+1}$ with the temperature $a_{n+1}/2\pi$. \textit{In fact, the Rindler frame $R_{n+1}$ attributes to all the Rindler vacuum states of $R_1, R_2, ... R_n$, as well as to the inertial vacuum state, the same temperature $a_{n+1}/2\pi$.} We further show that our result is discontinuous in an essential way in the coordinate shift parameters. For a Rindler frame $R_i$, this thermality {\it turns on} with smallest non-zero $\ell_i$ allowed in the semiclassical framework and remains insensitive to $(\ell_i,a_{i-1})$ thereafter, indicating its universal Planckian origin. Similar structures can be introduced in the right wedge of any spacetime with bifurcate &amp;#xD;Killing horizon, like, for e.g., Schwarzschild spacetime. Apart from providing unsuppressed observables capturing Planck scale effects, these results have important implications for quantum gravity when flat spacetime is treated as the ground state of quantum gravity.&amp;#xD;Furthermore, a frame with the shift $\ell$ and the corresponding acceleration parameter $a(\ell)$ can be thought of as a Rindler frame which is instantaneously comoving with the Einstein's elevator moving with a variable acceleration. Our result suggests that the quantum temperature associated with such an Einstein's elevator is the same as that defined in the comoving Rindler frame. The implications of these results are wide ranging, from having a definitive signature of Planck shifts in the horizon to the existence of a new set of observers in black hole exterior having thermodynamic description of the horizon they perceive.

Kinjalk Lochan

Thanu Padmanabhan

A nested sequence of inequivalent Rindler vacua : Universal Relic Thermality of Planckian origin

嵌套不等价的伦德勒真空序列：普朗克起源的普适遗迹热性

Abbreviation	Class. Quantum Grav.
Journal Impact	3.66
Quartiles(Global)	QUANTUM SCIENCE & TECHNOLOGY(Q2)

ISSN	0264-9381, 1361-6382
h-index	188

Publication Information	Publisher: IOP Publishing Ltd.，Publishing cycle: Semimonthly，Journal Type: journal，Open Access Journals: No
Basic data	Year of publication: 1984，Proportion of original research papers: 99.44%，Self Citation Rate:11.10%， Gold OA Rate: 26.46%
Average review cycle	网友分享经验：较快,2-4周
Average recruitment ratio	网友分享经验：较易

Classical and Quantum Gravity

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