Gravitational Wave Physics and Astrophysics with LIGO

该奖项支持相对论和相对论天体物理学的研究，它解决了NSF“宇宙之窗”大构想的优先领域。引力波（GW）物理学和天文学已经进入了一个新的时代：引力波瞬态事件（到目前为止，来自包含黑洞和/或中子星的紧凑双星系统的合并）在LIGO和Virgo探测器的前三次观测运行（O1, O2, O3）中经常被探测到。在第四次观测运行（O4）中，预计将于2022年12月开始，持续一年，KAGRA探测器也将参与其中，LIGO和Virgo探测器将提高对遥远源的灵敏度。这将导致从紧密双星合并中发现GW的空前速度，以及从其他天体物理来源（如随机GW背景）发现许多GW的潜力。事实上，可能会发现全新种类的GW源。这些观测将使从基础物理学到天文学、天体物理学和宇宙学的大量研究成为可能。对双黑洞合并的观测被用来理解恒星演化和双星的形成、演化和死亡。它们使广义相对论在强场、高动态的引力体系中得到了独特而有力的检验。对双中子星并合的观测使得对核状态方程的约束，对局部哈勃-勒梅特参数的独特测量，以及对宇宙中元素形成起源的见解成为可能。拟议的工作，在LIGO实验室和LIGO， Virgo和KAGRA （LVK）合作下，重点是开发方法，利用高度优化的搜索管道，在嘈杂的数据中自信地识别来自天体物理源的弱GW信号，并在其天体物理背景下解释结果。这些方法将进一步发展并应用于LVK O4运行的数据，并将吸取的经验教训纳入未来观测运行的适当准备中。各种活动，包括来自当地初中和高中的学生和教师，指导暑期本科生研究人员，组织和参与GW开放数据研讨会，旨在使引力波科学的这些进步能够被广泛的人和团体所接受。本工作致力于在2023- 2025财年（LIGO的观测运行O4和O5）中发现和分析LIGO、Virgo和KAGRA探测器的引力波信号。具体的科学目标是：(a)使用两个LSC“旗舰”搜索管道PyCBC和gstlal，从LIGO、Virgo和KAGRA的数据中识别出紧凑双星合并的GW信号；(b)通过搜索合并后的GW“回声”，搜索来自CBCs的GWs中的非张量极化，以及搜索来自BBH合并的信号波形中的超gr参数，对作为控制双黑洞（BBH）合并的强场引力理论的广义相对论进行更灵敏的测试；(c)从紧密双星并合中对GW信号的强引力透镜进行更深入的搜索——GW事件对的识别，包括亚阈值事件候选，以及联合参数估计；(d)提高单事件天体物理参数估计的效率和鲁棒性，准确准确地推断致密天体的质量和自旋；(e)使用来自O4和O5的更大的事件计数来进一步发展我们对BBH合并率作为质量、自旋和宇宙红移的函数的理解。这项工作将建立在所有这些工作的现有专业知识和经验的基础上，并通过自动化日常任务将其扩展到频繁检测的时代。这些努力的结果将使我们能够自信地探测到频繁发生的GW事件，并使所获得的信息及时地提供给LSC、天文学界和公众，以便这些团体能够充分利用这些信息来推进引力波天文学。为了使引力波科学能够为更广泛的人群和团体所接受，将开展以下活动：在LIGO SURF/REU项目中培训和指导各种本科生；通过GW开放科学中心支持开放科学；组织并参与年度GW开放数据研讨会；利用科学计算作为工具，通过在线教程和与当地学校的STEM教师联系，吸引高中生和本科生；通过参观当地的初中和高中STEM博览会和教室，参与K-12的外展活动，并与公众交流。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award supports research in relativity and relativistic astrophysics, and it addresses the priority areas of NSF's "Windows on the Universe" Big Idea. Gravitational-wave (GW) physics and astronomy has entered a new era: GW transient events (so far, from the merger of compact binary systems containing black holes and/or neutron stars) detected with the LIGO and Virgo detectors in their first three observing runs (O1, O2, O3) are frequent. In the fourth observing run (O4), estimated to begin in December 2022 and continuing for one year, the KAGRA detector will also participate, and the LIGO and Virgo detectors will have increased sensitivity to distant sources. This will result in unprecedented rates of discovery of GWs from compact binary mergers, and the potential for many discoveries of GWs from other astrophysical sources such as a stochastic GW background. Indeed, entirely new classes of GW sources may be discovered. These observations will enable a wealth of studies, ranging from fundamental physics to astronomy, astrophysics and cosmology. Observations of binary black hole mergers are used to understand stellar evolution and the formation, evolution and death of binaries. They enable uniquely powerful tests of general relativity in the strong-field, highly-dynamical regime of gravity. Observations of binary neutron star mergers enable constraints on the nuclear equation of state, unique measurements of the local Hubble-Lemaitre parameter, and insights into the origins of element formation in the universe. The proposed work, in coordination with the LIGO Laboratory and LIGO, Virgo and KAGRA (LVK) Collaborations, focuses on the development of methods to confidently identify weak GW signals from astrophysical sources in the noisy data, using highly optimized search pipelines, and interpret the results in their astrophysical context. These methods will be further developed and applied to data from the LVK O4 run, and lessons learned will be incorporated into appropriate preparation for future observing runs. A variety of activities involving students and teachers from local middle and high schools, mentoring summer undergraduate research fellows, and organizing and participating in GW Open Data Workshops, aim to make these advances in gravitational wave science accessible to a broad range of people and groups.This work is devoted to discovering and analyzing gravitational-wave (GW) signals in the LIGO, Virgo and KAGRA detectors during FY2023-FY2025 (LIGO's observing runs O4 and O5). Specific scientific goals are: (a) Identifying GW signals from compact binary mergers in data from LIGO, Virgo, and KAGRA, using two of the LSC "flagship" search pipelines, PyCBC and gstlal; (b) performing ever more sensitive Tests of General Relativity as the theory of strong-field gravity governing binary black hole (BBH) mergers, through searches for post-merger GW "echoes", searches for non-tensorial polarizations in GWs from CBCs, and searches for beyond-GR parameters in signal waveforms from BBH mergers; (c) performing ever deeper searches for strong gravitational lensing of GW signals from compact binary mergers - the identification of GW event pairs, including sub-threshold event candidates, and joint parameter estimation; (d) improving the efficiency and robustness of single-event astrophysical parameter estimation to infer the masses and spins of the compact objects with accuracy and precision; and (e) using the much larger event count from O4 and O5 to further develop our understanding of the BBH merger rate as a function of mass, spin, and cosmological redshift. The work will build on existing expertise and experience in all of these efforts, and extend them to the era of frequent detections by automating routine tasks. The results of these efforts will make it possible to make confident detections of GW events as they become frequent, and make the information obtained available to the LSC, to the astronomical community, and to the public, promptly, so that they can be fully exploited by those communities to advance gravitational-wave astronomy. In order to make gravitational wave science accessible to a broad range of people and groups, the following activities will be pursued: training and mentoring a diverse range of undergraduate students in the LIGO SURF/REU program; supporting open science through the GW Open Science Center; organizing and participating in annual GW Open Data Workshops; using scientific computing as a tool to engage high school and undergraduate students through online tutorials and through outreach to STEM teachers at local schools; and engaging in K-12 outreach and communicating with the general public, through visits to local middle- and high-school STEM fairs and classrooms.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.