Gravitational Wave Sources from Dense Star Clusters

大多数恒星形成于密集的星团中。最大的星团包含数百万颗恒星。这些恒星的质量，在诞生时，覆盖范围很广。质量最大的恒星在短短几百万年内就会结束生命，留下黑洞或中子星的残余。在几十亿年的时间里，中等质量的恒星会产生更多的大质量白矮星残骸。星团本身通常会持续存在数十亿年。因此，今天观测到的许多星团可能包含大量很久以前形成的黑洞和中子星，以及大量的白矮星。研究人员将使用计算机模拟来研究密集星团中所有致密残留物（黑洞、中子星和白矮星）的动态相互作用。这些模型将帮助天文学家解释观测数据。这项工作也有天文学以外的应用。特别是，为这项工作开发的计算方法将引起物理学和天文学以外的科学家的兴趣，因为用于模拟相互作用的密集星团的技术在科学和工程中具有广泛的相关性。这项工作还将有助于维持研究人员在计算天体物理学方面以学生为导向的研究计划。参与的研究生将指导并与本科生密切合作。调查人员将努力从传统上代表性不足的群体中招募学生。教育和公众宣传活动将利用调查人员与芝加哥阿德勒天文馆和西北大学迪尔伯恩天文台的密切联系。将进行最先进的n体模拟，以研究各种星团环境中紧凑物体的形成和演化。主要的焦点将放在紧致双星的产生上，它们可能是引力波和高能辐射的强大来源，以及由紧致物体的碰撞和近距离接触引发的瞬态源。这项工作将解决有关致密星团中致密物体的形成和动态演化的关键问题，包括它们与其他恒星的强烈相互作用。紧密残余物与其他恒星相互作用产生的电磁瞬变可能包括各种x射线和伽马射线爆发源，以及许多在大时域天文学调查的新时代非常感兴趣的光学瞬变。此外，所有通过动态相互作用形成的致密双星都是强大的引力波源，其中一些会有强大的电磁对应物，使它们成为多信使天文学的关键目标。因此，该奖项推进了NSF“宇宙之窗：多信使天体物理学时代”大构想的目标。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。

Most stars form in dense clusters. The largest star clusters contain many millions of stars. The masses of these stars, when born, cover a broad range. The most massive stars end their lives in as little as a few million years and leave behind remnant black holes or neutron stars. Much larger numbers of massive white dwarf remnants are produced from intermediate-mass stars in a few billion years. The star clusters themselves often continue to live for many billions of years. Therefore, many of the star clusters observed today can contain large numbers of black holes and neutron stars formed a long time ago, as well as large populations of white dwarfs. The investigators will use computer simulations to study the dynamical interactions of all compact remnants (black holes, neutron stars, and white dwarfs) in dense star clusters. These models will help astronomers interpret observational data. This work also has applications beyond astronomy. In particular, the computing methodology developed for this work will be of interest to scientists outside of physics and astronomy, since the techniques used to model dense clusters of interacting stars have broad relevance in science and engineering. This work will also help maintain the investigators' student-oriented research program in computational astrophysics. The graduate students involved will mentor and work closely with undergraduate students. The investigators will strive to recruit students from traditionally underrepresented groups. Education and public outreach activities will take advantage of the investigators' close ties to the Adler Planetarium in Chicago and the Dearborn Observatory on the Northwestern University campus. State-of-the-art N-body simulations will be performed to study the formation and evolution of compact objects in a variety of star cluster environments. The main focus will be on the production of compact binaries, which can be strong sources of gravitational waves and high energy radiation, as well as transient sources triggered by collisions and close encounters of compact objects. The work will address key questions concerning the formation and dynamical evolution of compact objects in dense star clusters, including their strong interactions with other stars. The electromagnetic transients produced through interactions of compact remnants with other stars potentially include a variety of X-ray and gamma-ray burst sources, as well as many optical transients of great current interest in the new era of large time-domain astronomy surveys. Additionally, all compact binaries formed through dynamical interactions are strong sources of gravitational waves, and some will have strong electromagnetic counterparts, making them key targets for multi-messenger astronomy. This award thus advances the goals of the NSF's "Windows on the Universe: The Era of Multi-Messenger Astrophysics" Big Idea.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.