Searching for Long-Lasting Gravitational-Wave Signals with Second-Generation Gravitational-Wave Detectors

用第二代引力波探测器寻找持久的引力波信号

• 批准号: 1204944
• 负责人: Vuk Mandic
• 金额: $ 36万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-15 至 2015-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1204944&HistoricalAwards=false
• 关键词: Searching; Long; Lasting; Gravitational; Wave

Predicted by Einstein's Theory of General Relativity, gravitational waves have evaded direct detection for nearly a century due to their exquisitely small amplitudes. However, with the arrival of the second-generation gravitational-wave detectors, such as Advanced LIGO and Advanced Virgo, first detections of gravitational waves produced in astrophysical and cosmological processes are expected to be made over the next decade. This project focuses on gravitational waves emitted on long time scales, such as the stationary stochastic gravitational-wave background (SGWB) generated by an incoherent superposition of signals from many independent sources. The project also targets transient gravitational-wave signals on the time-scales of minutes, hours or longer, generated by a variety of astrophysical processes such as dynamically formed black-hole binaries or fragmentation in accretion disks around black holes. Cross-correlation techniques will be applied to the first data to be acquired by the second-generation detectors in search for these long-lasting signals. With over 1000 times better sensitivity than the latest published results, these searches will probe and constrain a number of proposed SGWB models. Furthermore, the SGWB models will be systematically studied to precisely identify the open science questions within these models that could be pursued by the second-generation detectors. Examples of such open questions include: What is the equation of state in neutron stars? What is the coalescence rate of binary neutron stars? Which cosmological models of SGWB are accessible to the second-generation detectors?This project is expected to have a strong impact on cosmology and astrophysics. For example, the SGWB is expected to be generated just moments after the Big Bang, and hence may contain unique information about the first moments in the evolution of the universe and about the physics of highest energy scales, which is otherwise not accessible in laboratories. Similarly, the SGWB could be of astrophysical origin: for example, summing up contributions from all binary neutron stars, binary black holes, magnetars, or Supernovae in the universe leads to a stochastic gravitational-wave "foreground" that contains information about these most violent objects and events in the universe. The long-lasting transient gravitational-wave signals will also provide information about the astrophysical objects and processes that generated them. For example, direct detection of gravitational-wave signals produced by dynamically formed black hole binaries would shed light on the population of black holes that lurk in the inner regions of nearby galaxies, revealing their density and velocity distribution.

根据爱因斯坦的广义相对论的预测，引力波由于其极其微小的振幅，已经逃避了近世纪的直接探测。然而，随着第二代引力波探测器的到来，如Advanced LIGO和Advanced Virgo，预计在未来十年内将首次探测到天体物理和宇宙学过程中产生的引力波。该项目的重点是长时间尺度上发射的引力波，例如由来自许多独立源的信号的非相干叠加产生的平稳随机引力波背景（SGWB）。该项目还针对由各种天体物理过程（如动态形成的黑洞双星或黑洞周围吸积盘的碎片）产生的时间尺度为分钟、小时或更长的瞬态引力波信号。互相关技术将应用于第二代探测器获取的第一批数据，以寻找这些持久的信号。这些搜索的灵敏度比最新公布的结果高出1000倍以上，将探测和约束许多拟议的SGWB模型。此外，将系统地研究SGWB模型，以精确识别这些模型中可以由第二代探测器追求的开放科学问题。这类开放性问题的例子包括：中子星的状态方程是什么？中子双星的合并速率是多少？SGWB的哪些宇宙学模型是第二代探测器可以访问的？该项目预计将对宇宙学和天体物理学产生重大影响。例如，SGWB预计在大爆炸后的瞬间产生，因此可能包含有关宇宙演化的第一时刻和最高能量尺度物理学的独特信息，否则在实验室中无法获得。类似地，SGWB也可能是天体物理学的起源：例如，将宇宙中所有的双星中子星、双星黑洞、磁星或超新星的贡献加起来，就会产生一个随机引力波的“前景”，其中包含了宇宙中这些最猛烈的物体和事件的信息。持久的瞬态引力波信号还将提供有关天体物理对象和产生它们的过程的信息。例如，直接探测由动态形成的黑洞双星产生的引力波信号，将有助于了解潜伏在附近星系内部区域的黑洞数量，揭示它们的密度和速度分布。