一种引力波天线的调谐方法

目前理论上预期的天体引力波源在低频段的引力辐射比较丰富［１－４］．另一方面,目前使用的引力波天线绝大多数是机械共振天线,这类天线的Ｑ值大都很高（１０４以上）,频带甚窄（当ｖ～１０ＨＺ时,Δｖ≤０．０１Ｈｚ）,在对某一特定的窄带引力辐射进行探测时很容易失调［５］．因此,为了更好地探测引力波,并做到容易对准和跟踪它,自然希望天线具有比较低的共振频率和能够在一定的频率范围内方便地调谐．作者曾在扭摆?...     

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。     

黑洞的合并

最近利用引力观测所的激光干涉仪（Laser Interferometer Gravitational—Wave Observatory，LIGO）和空间天线激光干涉仪（Laser Interferometer Space Antenna LISA）的探测器对两个黑洞在碰撞时辐射的引力波进行了精确的观测与计算．两个黑洞进行碰撞时，在它们的周围会向外发射出巨大的突发性的引力波，这些波非常有利于探测器对它们的搜索．     

微弱信号检测讲座 第四讲 引力波检测

类似于投石激起平静水面的涟漪,引力波（又称引力辐射）是物质加速运动使引力场产生的波动．广义相对论预言：引力波类似于电磁波,也是横波,并以光速传播,且具偏振性质．引力波产生的潮汐力能使两分离粒子间的距离产生变化,检测这些变化可以了解波源物质运动的信息．理论计算表明,物质运动辐射引力波以及物质对引力波的吸收,其效率都十分低．这是因为引力相互作用十分微弱,而动量守恒定律又决定了不可能有偶极引力辐射?...     

集中质量音叉式引力波天线与Vela星引力辐射探测的探讨

本文提出并计算了一种接收Vela星引力辐射的集中质量音叉式机械谐振型低频天线。指出,由于Vela星引力波信号的连续性和单色性,可以采用信号积累方法提高接收灵敏度。最后给出了灵敏度可以达到目前理论估计的Vela星引力辐射强度的天线参数。此种天线也适用于其他低频引力波探测。 关键词：     

软光子定理与电磁学记忆效应

在广义相对论体系中,引力波指的是时空弯曲的涟漪以波的形式由辐射源向外传播。1916年爱因斯坦基于广义相对论预言了其存在性。引力波不存在于牛顿的经典引力理论中,因为牛顿引力理论假设物质之间的引力相互作用是一种超距作用,即传播的速度是无穷大的。所以引力波也是验证广义相对论的重要现象之一。自从爱因斯坦预言了引力波之后,物理学家和天文学家在实验探测中做出了无数的努力。由于直接探测引力波对实验精度的要求极高,在爱因斯坦预言整整100年之后,LIGO探测器才首次直接探测到了引力波信号。该结果也是2016年最重大科学成果之一。     

基于普通物理分析LIGO引力波数据

LIGO小组首次直接探测到双黑洞并合过程中产生的引力波辐射,打开了观测宇宙的一个全新窗口.本文利用牛顿力学,量纲分析,以及将引力波与电磁波类比等方法分析了LIGO小组观测到的引力波数据.这些简单的分析能够解释LIGO数据的主要物理结论,估算结果在数量级上与LIGO数据基本一致.本文对黑洞质量,引力波源到地球的距离,双黑洞并合前的初始距离,以及辐射的总能量等参数的估算与LIGO和VIRGO小组给出的结论基本一致.(2017美国物理教师协会)     

测量宇宙膨胀的理想工具——中子星黑洞并合

正正在萌芽的引力波天文学提供了若干前所未有的机遇。例如,依据引力波测量得到的距离,人们即可确定宇宙各处的膨胀。麻省理工学院Vitale和哈佛大学Chen的研究表明,黑洞与中子星并合这类特殊的引力波源可能是测量宇宙膨胀率的最佳工具。当今宇宙的膨胀率由哈勃常数     

利用脉冲星测到引力波了?

想象一下,能将引力波探测器延伸至银河系的边缘吗?北美纳赫兹引力波天文台(NANOGrav)正是这样的组织,通过监测河内若干脉冲星的脉冲到达时间来测量距离的改变.2020 年 NANOGrav 宣称发现脉冲到达时间出现涨落,可能是纳赫兹引力波的证据.黑洞合并可产生这种引力波,但不排除其他波源,包括宇宙弦、宇宙早期黑洞形成...     

封面故事

<正>北京时间2017年10月16日晚,激光干涉引力波天文台(LIGO)科学合作组织和处女座引力波探测器(Virgo)合作组织联合召开发布会,宣布再次探测到时空的涟漪——引力波及其伴随的电磁信号,正式编号GW170817。这是人类首次直接探测到两颗中子星并合产生的引力波事件,发生在1.3亿光年外的编号为NGC 4993的星系中。此次引力波事件具有极为重要的意义,引力波及其电磁对应体的发现,有助于科学家结合不     

Evaluation and preliminary measurement of the interaction of a dynamical gravitational near field with a cryogenic gravitational wave antenna

We present a detailed analysis of the effect of the gravitational field generated by a small rotating quadrupole on a graviational wave antenna and we report on the preliminary measurement of this effect on the Explorer 2270 kg cryogenic gravitational wave antenna of the Rome group. The induced signal had an amplitude twenty times larger than the detector noise when the antenna was equipped with an FET amplifier and was easily detected without requiring integration in time. We remark that with this method we were able to make an absolute calibration of a gravitational wave antenna.     

Quantum speed meter in laser gravitational antennas

A method of enhancing the sensitivity of laser gravitational antennas based on tracking of the velocity of the antenna reflectors instead of conventional tracking of their displacement is considered. This method allows one to overcome the standard quantum detection limit for a weak force. An optical scheme of a gravitational wave detector on the basis of a speed meter is considered. The formulas for the limiting sensitivity of the given scheme taking optical losses into account are obtained. The possibility of realizing the considered measurement method in presently existing laser gravitational antennas is analyzed.     

Gravitational wave detection: stochastic resonance method with matched filtering

Along with the development of the interferometric gravitational wave detector, we enter into an epoch of the gravitational wave astronomy, which will open a brand new window for astrophysics to observe our universe. However, the gravitational wave detection is a typical weak signal detection, and this weak signal is buried in a strong instrument noise. To our knowledge, almost all of the data analysis methods in gravitational wave detection at present are based on a matched filtering. So it is desirable to take advantage of stochastic resonance methods. However, the all of the stochastic resonance methods are general based on a Fourier transformation and fall short of the matched filtering as a usable technique. In this paper we relate the stochastic resonance to the matched filtering. Our results show that the stochastic resonance can indeed be combined with the matched filtering for both the periodic and the non-periodic input signal. This encouraging result will be the first step to apply the stochastic resonance to the matched filtering in gravitational wave detection. Moreover, based on the matched filtering, we firstly propose a novel measurement method for the stochastic resonance which is valid for both the periodic and the non-periodic driven signal.     

Experimental study of the dynamic Newtonian field with a cryogenic gravitational wave antenna

We present an experiment performed to study the behaviour of the dynamic gravitational interaction at laboratory scale. We used as field generator a mass quadrupole rotating in the range of 460 Hz and we detected the acceleration field with the cryogenic gravitational wave antenna Explorer of the Rome group. We report the measurements of this interaction as a function of the distance between the field source and the detector. An upper limit on the parameters of a Yukawa-like potential, modeling an hypotetic deviation from the Newtonian law of gravity, is derived. Received: 14 June 1998 / Published online: 16 September 1998     

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.     

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.     

On the Massive Antenna Suspension System in the Brazilian Gravitational Wave Detector SCHENBERG

SCHENBERG is a resonant-mass gravitational wave detector built in Brazil. Its spherical antenna, weighting 1.15 t, is connected to the outside world by a suspension system whose main function is to attenuate the external seismic noise. In this work, we report how the system was modeled using finite elements method. The model was validated on experimental data. The simulation showed that the attenuation obtained is of the order of 260 dB, which is sufficient for decreasing the seismic noise below the level of the thermal noise of the detector operating at 50 mK.     

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.     

Optical design of a high power mode-cleaner for AIGO

Laser beam geometry variations such as beam jitter and frequency fluctuations are a critical source of noise in the output signal of a laser interferometer gravitational wave detector. In order to minimise this noise a resonant vibration isolated optical filter or mode-cleaner is required. For advanced gravitational wave detectors such a mode-cleaner is required to be able to handle transmitted power ∼100 W, and an internal circulating power of 45 kW. This paper addresses the design requirements of such a mode-cleaner. We characterise the mode-cleaner requirements and the effects of high laser power on the optics and its consequence on the suppression of higher order modes.