Living Reviews in Relativity ( IF 26.3 ) Pub Date : 2019-10-14 , DOI: 10.1007/s41114-019-0022-2 Jan Harms
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Terrestrial gravity fluctuations are a target of scientific studies in a variety of fields within geophysics and fundamental-physics experiments involving gravity such as the observation of gravitational waves. In geophysics, these fluctuations are typically considered as signal that carries information about processes such as fault ruptures and atmospheric density perturbations. In fundamental-physics experiments, it appears as environmental noise, which needs to be avoided or mitigated. This article reviews the current state-of-the-art of modeling high-frequency terrestrial gravity fluctuations and of gravity-noise mitigation strategies. It hereby focuses on frequencies above about 50 mHz, which allows us to simplify models of atmospheric gravity perturbations (beyond Brunt–Väisälä regime) and it guarantees as well that gravitational forces on elastic media can be treated as perturbation. Extensive studies have been carried out over the past two decades to model contributions from seismic and atmospheric fields especially by the gravitational-wave community. While terrestrial gravity fluctuations above 50 mHz have not been observed conclusively yet, sensitivity of instruments for geophysical observations and of gravitational-wave detectors is improving, and we can expect first observations in the coming years. The next challenges include the design of gravity-noise mitigation systems to be implemented in current gravitational-wave detectors, and further improvement of models for future gravitational-wave detectors where terrestrial gravity noise will play a more important role. Also, many aspects of the recent proposition to use a new generation of gravity sensors to improve real-time earthquake early-warning systems still require detailed analyses.
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地球重力波动
地球重力波动是地球物理学和涉及重力的基础物理实验(例如引力波观测)中各个领域科学研究的目标。在地球物理学中,这些波动通常被视为携带有关断层破裂和大气密度扰动等过程信息的信号。在基础物理实验中,它表现为环境噪声,需要避免或减轻。本文回顾了高频地球重力波动建模和重力噪声缓解策略的最新技术。它特此关注大约 50 mHz 以上的频率,这使我们能够简化大气重力扰动模型(超出 Brunt-Väisälä 体系),并且还保证弹性介质上的重力可以被视为扰动。在过去的二十年里,人们进行了广泛的研究来模拟地震和大气场的贡献,特别是引力波领域的贡献。虽然尚未最终观测到 50 mHz 以上的地球重力波动,但地球物理观测仪器和引力波探测器的灵敏度正在提高,我们预计将在未来几年进行首次观测。接下来的挑战包括设计在当前引力波探测器中实施的重力噪声缓解系统,以及进一步改进未来引力波探测器的模型,其中地球重力噪声将发挥更重要的作用。此外,最近提出的使用新一代重力传感器来改进实时地震预警系统的许多方面仍然需要详细分析。