用零输出的设备探测引力波

理论估计传到地球上的引力波非常弱,激光干涉引力波探测器被设计用来探测引力波,在没有引力波传来时,激光干涉引力波探测器应该是零输出。为达到这样的目的,必须和众多的噪声作斗争。     

The Three-Arm Michelson-Fabry-Perot Detector for Gravitational Waves

A three-arm Michelson-Fabry-Perot detector for gravitational waves is designed.It consists of three MichelsonFabry-Perot interferometers,one for each pair of arms.The new detector can be used to confirm whether the gravitational waves are in general relativity polarization states and to set the strong constraints on non-GR gravitational wave polarization states.By the new detectors,the angular resolution of sources can be improved significantly.With the new detector,it is easier to search for and confirm a gravitational wave signal in the observation data.     

Physical Explanation of Influence of Twin and Three Satellite Formation Mode on the Accuracy of Earth's Gravitational Field

The simulated results of the influence of twin and three satellite formation mode on the accuracy of GRACE Earth＇s gravitational field are interpreted from the viewpoint of physics. Because the effective satellite observation information of Earth＇s gravitational field recovery from three-satellite formation mode is only one time more than that of twin satellites, the improvement of the accuracy of Earth＇s gravitational field is far lower than one order of magnitude based on the simple two-times differences between three satellites. Three efficient ways of improving largely the accuracy of measurement of the Earth＇s gravitational field in the future international satellite gravity measurement programme, including proper decrease of satellite orbital altitude, the increase of accuracy from key payloads and an innovation of satellite observation mode are proposed.     

空间引力波探测望远镜初步设计与分析

引力波的直接观测已开启引力波天文学的新篇章,爱因斯坦的百年预言终获证实。空间引力波探测器使得探测0.1 m Hz~1 Hz频段丰富的引力波源成为可能,与地面引力波探测器互为补充,才可实现更加宽广波段的引力波探测,揭开宇宙早期的更多秘密。空间激光干涉引力波探测采用外差干涉测量技术,测量间距百万公里的两自由悬浮测试质量间10 pm量级的变化量。望远镜是激光干涉测量系统的重要组成部分,1 pm的光程稳定性及苛刻的杂散光要求,不同于传统的几何成像望远镜。本文根据空间太极计划任务需求,对望远镜的功能及技术要求进行了分析,并完成了原理样机的初步方案设计,针对百万公里远场波前分布,分析了望远镜系统的敏感性,同时完成了在轨光机热集成仿真,为后面原理样机的研制奠定了技术基础。     

Shape and gravitational field of the ellipsoidal satellites

The shape and gravitational field of ellipsoidal satellites are studied by using the tidal theory. For ellipsoidal satellites, the following conclusions were obtained: Firstly, in the early stage of the satellite formation, strong tidal friction allowed the satellites move in a synchronous orbit and evolve into a triaxial ellipsoidal shape. Because the tidal potential from the associated primary and the centrifugal potential from the satellite spin are nearly fixed at the surface, the early satellites are the viscoelastic celestial body, and their surfaces are nearly in the hydrostatic equilibrium state. The deformation is fixed in the surface of the satellite. By using the related parameters of primary and satellite, the tidal height and the theoretical lengths of three primary radii of the ellipsoidal satellite are calculated. Secondly, the current ellipsoidal satellites nearly maintain their ellipsoidal shape from solidification, which happened a few billion years ago. According to the satellite shape, we estimated the orbital period and spinning angular velocity, and then determined the evolution of the orbit. Lastly, assuming an ellipsoidal satellite originated in the hydrostatic equilibrium state, the surface shape could be determined by tidal, rotation, and additional potentials. However, the shape of the satellite’s geoid differs from its surface shape. The relationship between these shapes is discussed and a formula for the gravitational harmonic coefficients is presented.     

Optical detector topology for third-generation gravitational wave observatories

The third generation of gravitational wave observatories, with the aim of providing 100 times better sensitivity than currently operating interferometers, is expected to establish the evolving field of gravitational wave astronomy. A key element, required to achieve this ambitious sensitivity goal, is the exploration of new interferometer geometries, topologies and configurations. In this article we review the current status of the ongoing design work for third-generation gravitational wave observatories. The main focus is the evaluation of the detector geometry and detector topology. In addition we discuss some promising detector configurations and potential noise reduction schemes.     

Forty Years to the Artemovsk Scintillation Detector for Neutrinos

The current status of the ASD (Artemovsk scintillation detector) experiment aimed at search for a neutrino flux from gravitational collapses of stellar cores is presented. Experimental data obtained for 40 years of operation of the detector situated in a salt mine at a depth of 570 mwe are processed. The results obtained by calculating the expected signal in the detector on the basis of two models of supernova explosion are described. No candidates for neutrino bursts from gravitational star collapses have been revealed: the limit on the frequency of gravitational collapses was found to be less than one event per 17.15 yr at a 90% confidence level (f_col < 0.058 yr^?1).     

论引力波探测器方位与引力波源方位间的关系

本文从计算棒状引力波天线的指向性函数出发,讨论了引力波源的方位和天线棒方位之间的关系,找到了从符合实验数据求出引力波源方位以及利用单一引力波探测器对连续引力波源的定位方法。所得的结果也适用于其他形式的一维引力波天线。一旦引力波探测器的灵敏度达到足以确定引力波强度时,本文的结果无疑对引力波天文学将是很有意义的。 关键词：     

Energy localization in general relativity: A new hypothesis

A new hypothesis for energy localization in general relativity is introduced which is based upon the fact that the energy-momentum conservation laws are devoid of content in vacuum. The vanishing of pseudotensor components forms the basis of coordinate conditions consistent with the above. The implication is that energy is localized where the energy-momentum tensor is nonvanishing. As a consequence, gravitational waves are not carriers of energy in vacuum. A detailed analysis of a Feynman detector interacting with a plane gravitational wave is consistent with the hypothesis. The fact that there has never been a confirmed direct energy transfer to a detector via gravitational radiation is also consistent with the hypothesis.     

On a New Observable for Measuring the Lense–Thirring Effect with Satellite Laser Ranging

For a pair of twin Earth orbiting artificial satellites placed in identical orbits with supplementary inclinations, in addition to the sum of the residuals of the nodal rates, already proposed for the LAGEOS–LARES mission, also the difference of the residuals of the perigee rates could be employed, in principle, for measuring the general relativistic Lense–Thirring effect. Indeed, on one hand, the gravitomagnetic secular precessions of the perigees of two supplementary satellites in identical orbits are equal and opposite, and, on the other, the classical secular precessions induced by the multipolar expansion of the terrestrial gravitational field are equal, so that their aliasing effect cancels out in the difference of the perigees' rates. If the eccentricities of the two satellites would be chosen to be equal, contrary to the LAGEOS–LARES project, such cancellation would occur at a very accurate level. Among the time–dependent perturbations, the proposed observable would allow to cancel out the even and odd zonal gravitational tidal perturbations and some non–gravitational perturbations. With a proper choice of the inclination of the two satellites, the periods of all the uncancelled time–dependent perturbations could be made short enough to allow to fit and remove them from the signal over observational time spans of a few years. The linear perturbation induced by the terrestrial Yarkovski–Rubincam effect would affect the proposed measurement at a level well below 10^–3.     

Underground spherical gravitational wave detector

Recently significant advancements have been made towards the realization of a large spherical gravitational wave detector. Research and development activities have already begun in several countries. We present here the main features and capabilities of a spherical gravitational wave detector. In particular, we discuss the interaction between a spherical antenna and cosmic rays that may require a large detector to be placed underground.     

The possibility of using cryofiber interferometer as detector of gravitational waves

The history of the question on the possibility of detecting gravitational waves, whose existence is predicted by the General Relativity Theory, is briefly presented. The schemes of cryofiber interferometer, which we propose to use as detector of gravitational waves with amplitude |δg _ij | = 10^?20, are described. We also consider other versions of the use of cryofiber interferometer in both applied and fundamental context, including laboratory experiments in which according to the estimates dark energy density variations can be detected. We describe briefly the optical scheme of a compact interferometric detector of vibrations of a mirror fixed at the end of a massive gravitational antenna; the compactness admits construction of a cryogenic version with cooling of all the elements of such a recording system.     

Quadrupole mass-detector in field of weak plane gravitational fields

A study has been made of the behavior of systems consisting of two test particles joined by a spring (quadrupole mass-detector) and placed in a field of weak plane monochromatic gravitational wave. It was shown that under transverse orientation of the detector the gravitational wave acting on such system sets it into oscillatory motion at a frequency equal to the frequency at which the source of the gravitational wave oscillates. In this case the role of the driving force is played by periodic variations in the equilibrium position with time. The gravitational wave does not act on the detector when it has a longitudinal orientation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 109–114, October, 1978.The author wishes to express his heartfelt gratitude to the participants in the small scientific seminar of the Gravitational Section of the Scientific and Technical Council at the Ministry of Higher Institutes of Learning of the USSR for their interest in the work and valuable critical comments.     

Astrophysics from data analysis of spherical gravitational wave detectors

The direct detection of gravitational waves will provide valuable astrophysical information about many celestial objects. Also, it will be an important test to general relativity and other theories of gravitation. The gravitational wave detector SCHENBERG has recently undergone its first test run. It is expected to have its first scientific run soon. In this work the data analysis system of this spherical, resonant mass detector is tested through the simulation of the detection of gravitational waves generated during the inspiralling phase of a binary system. It is shown from the simulated data that it is not necessary to have all six transducers operational in order to determine the source’s direction and the wave’s amplitudes.     

On the intrinsic entropy of the gravitational field

I show that in linearized general relativity it is impossible to construct a detector by the use of which the quantum state of the linearized gravitational field could be reliably determined. This is because there is no material satisfying the positive energy condition which can serve as a good conductor or absorber of gravitational radiation over a finite range of frequencies. If this property is true of the full theory then one can conclude that a certain proportion of both the energy and information carried by a gravitational wave is irreversibly lost, and that there is a correspondingintrinsic entropy associated with any distribution of gravitational radiation.     

Limitations of atom interferometry for gravitational wave observations in space

A paper published recently (Hogan et al. in Gen. Relativ. Gravit. 43:1953–2009, 2011) suggests the use of atom interferometry between satellites in Earth orbit to observe gravitational waves. The proposed altitude and satellite separation are about 1,000 and 30 km respectively. The difference in acceleration between clouds of ultracold atoms in atom interferometers near the two satellites would be detected by using laser beams between the interferometers. Because of the measurement path being very short compared with the million km or longer measurement path for a proposed laser interferometer gravitational wave antenna in space, the sensitivity to differential fluctuations in the laser phase as seen by the atoms in the two atom interferometers is very high. Problems introduced by this high sensitivity to spurious laser beam phase changes will be described in the first part of this paper. Then other limitations on the performance and on the suggested types of sources that could be observed will be discussed.     

The possibility of checking the equivalence principle in a null gravitational redshift experiment by a two-resonator laser system

A scheme of an optical detector is proposed for checking Einstein’s equivalence principle (EEP) in a null gravitational redshift experiment and for testing methods for calculating the length of a resonator in a weak variable gravitational field by recording the variations of the difference frequency of resonators caused by lunisolar variations of the geopotential in a double or a two-resonator laser system.     

Current programs of search for gravitational waves by terrestrial detectors

We discuss the problem of of detection the gravitational radiation which could be produced by relativistic objects in the Universe. After a brief sketch of the detector world net the attention is concentrated on present programs of search for conceivable signals expected in the frame of modern astrophysics. It is concluded that the probability of succeeding with the modern generation of gravitational detectors, sensitive to the metric perturbation on the order of 10⁻²¹, is low. One of the ways to increase the probability is a search for “astro-gravity correlations” where a gravitational detector noise background is analysed referring to the data of gamma-ray and neutrino detectors. Author dedicates this article to Prof. Jiří Bičák’s 60th birthday.     

On the Possibility to Construct Gravitational Eye

The possibility of modifying a conventional Cavendish torsion pendulum into a half-armed pendulum oscillator to measure the horizontal gravitational acceleration is discussed. A new kind of gravitational detector, gravieye, as we named, can be made by a proper combination of such oscillators to ＂see＂ remote objects and to be used, e.g. to detect the movement of huge mass at a long distance.     

On the electromagnetic detectors of gravitational waves

Summary The coefficients of the metric induced by a gravitational wave are calculated in a Fermi co-ordinate system naturally connected with an electromagnetic detector of gravitational waves. The correct form of the perturbation current is established and the results are compared with those found in the literature. Paper presented at the 2° Convegno Nazionale di Fisica Cosmica, held at L'Aquila, 19 May–2 June 1984.