地基射电望远镜和空间激光干涉仪的引力波探测

There is still no report of direct detection of gravitational waves (GW) since they were predicted in the general theory of relativity about 100 years ago. In addition to a few existing ground-based GW observatories, a space-borne Michelson-type Laser interferometer called New Gravitational wave Observatory (NGO) is now undergoing design and development in the European Union. Studies in the past few decades indicate that there will be a large population of double compact objects in the Galaxy emitting GW in the frequency band of 0.0001-1 Hz; this is also the working frequency band of the NGO. We propose to simulate the GW signal from the population of double compact objects in the Galaxy and local group using the General Relativity, Classical Theory of Fields, and the theory of formation and evolution of stars. The aim of this work is to obtain the birth and merger rates, physical properties and distribution of double compact objects in view of formation and evolution of stars, the superposition of GW signal emitted from the double compact objects, and the constraints on GW provided by precise timing of Galactic millisecond pulsars made by high sensitive radio telescopes. We are developing a computational algorithm to simulate the amplitude and polarization of GW from the double compact objects in the Galaxy and local group on the basis of our previous work. In order to understand and confirm the GW signal, we will compare the synthesized GW signal and the sensitivity of GW detector. Based on the calculations above, we are able to characterize the timing-residuals of Galactic millisecond pulsars, and compare our results with present radio observations and predict potential observations made by the next generation of radio telescopes. We will benefit from the proposed study through better understanding the nature of gravity. The success of observations of GW may reveal the 'dark side' of the universe.

从相对论预言引力波至今已有约100余年的历史，然而至今仍未直接探测到引力波。空间引力波探测器NGO的原理是使用类Michelson激光干涉仪测量当引力波通过仪器时，仪器周围空间振动的量级。在该仪器的最佳测量频率0.0001-1Hz，计算表明存在相对大量的双简并天体星族。本课题将结合相对论、场论和恒星星族形成演化理论数值模拟和研究银河系和局部宇宙内双简并天体星族产生的引力波信号。通过对该引力波信号的研究，我们进而计算高灵敏度射电望远镜对脉冲星星族测时的余差，限制从不同的天体，如银河系中心黑洞及邻近天体，系外超大质量双黑洞等发出的引力波信号。该研究将帮助我们证认和限制未来对引力波的观测，理解引力的本质。未来引力波探测仪的成功研制和对引力波的直接观测将使我们增强对宇宙"黑暗面"的认识。

相对论预言的引力波信号已经被美国激光干涉仪天文台探测到，这些高频信号被认为是由恒星质量双黑洞并合产生。银河系内可能存在大量双致密天体(双黑洞是其中一类)，它们产生的低频引力波背景信号尚未被探测到。我们理论上系统地研究了双致密天体在银河系的分布、诞生、并合率和数目，以及这些天体产生的引力波背景信号和其可探测性。我们结果表明这个背景信号可能各向异性和有震荡性，震荡的频率和强度由双致密天体的轨道参数分布决定。我们也理论上研究了脉冲星发出的射电脉冲信号被球面引力波引起的时空变化所调制的信息。此外，我们研究了一种转动干涉仪的噪音水平和作为引力波探测仪的灵敏度，该结果可以应用在高精度距离（或角度）测量和反馈控制技术的发展。