Unfolding the Dynamic and Colorful Lives of Compact Object Mergers

双星系统中两个天体（中子星和/或黑洞）的合并是引力波发射的来源，是重元素核合成的潜在场所，也是宇宙中其他地方看不到的高能天体物理过程的实验室。随着先进的引力波探测器的出现，直到最近天文学家才开始对这些过程施加直接的限制。在宇宙距离上探测到的短伽马射线暴（sgrb）也提供了一个独特而独立的窗口，可以了解紧凑物体合并的动态和丰富多彩的生活。在首席研究员（PI）的指导下，西北大学的一个研究小组将利用来自引力波天文台、地面望远镜和天基伽马射线和x射线任务的互补数据流：(i)制定引力波事件后电磁（EM）观测的后续策略，（ii）通过光学和近红外观测来对抗合并中重元素产生的理论模型，（iii）通过x射线观测对产生sgrb的合并比例进行限制，（iv）通过对其主星系的完整普查来破解合并前双星系统的历史。为了使这项研究以一种新颖的方式公开，PI将与埃文斯顿（伊利诺伊州）乡镇高中（ETHS）合作，该学校有一个校园天文馆。PI将利用天文馆作为一个场所，让学生参与研究材料，并让学生接触来自不同背景的天文学研究人员。研究小组将利用先前sgrb的推断特性来构建光曲线预测工具，以优化天文台在引力波事件后探测到EM对应物的机会。这些适应性强的工具将成为重要的社区资源，不仅可用于确定当前的观测策略，还可用于规划未来的电磁调查。该研究小组还将通过确定独立测量的抛射物质量和事件速率，对合并在使宇宙充满重元素方面的作用施加直接的观测限制。研究人员将对SGRB宿主星系和星系中心爆发的空间偏移量进行完整的普查。从这些观察中，研究人员将确定合并踢速和延迟时间的分布。这些分布是二元演化模型的重要输入，但它们具有高度的不确定性。该项目设计得很好，可以利用合并发现的两种方法：来自高级LIGO/Virgo的引力波发射和来自天基任务的伽马射线暴探测。对于这项提议的所有目标，研究小组将在高级LIGO/Virgo发现的致密天体合并的本地种群与它们的宇宙类似物之间建立至关重要的联系。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。

The mergers of two astronomical compact objects (neutron stars and/or black holes) in a binary system serve as sources of gravitational wave emission, potential sites of heavy element nucleosynthesis, and laboratories for high-energy astrophysical processes not seen elsewhere in the universe. With the onset of advanced gravitational wave detectors, only recently have astronomers begun to place direct constraints on these processes. Short gamma-ray bursts (SGRBs), which are detected at cosmological distances, also offer a unique and independent window into the dynamic and colorful lives of compact object mergers. A research group at Northwestern University, under the direction of the principal investigator (PI), will capitalize on complementary streams of data from gravitational wave observatories, ground-based telescopes and space-based gamma-ray and X-ray missions to: (i) develop informed follow-up strategies for electromagnetic (EM) observations following gravitational wave events, (ii) confront theoretical models of heavy element production in mergers with optical and near-infrared observations, (iii) place constraints on the fraction of mergers that produce SGRBs with radio through X-ray observations, and (iv) decipher the histories of the pre-merger binary systems with a complete census of their host galaxies. To make this research publicly accessible in a novel way, the PI will partner with Evanston (Illinois) Township High School (ETHS) which has an on-campus planetarium. The PI will use the planetarium as a venue for engaging students with research material and exposing students to Astronomy researchers from diverse backgrounds.The research group will utilize the inferred properties of previous SGRBs to build light curve prediction tools that will optimize an observatory's chance of an EM counterpart detection following a gravitational wave event. These adaptable tools will serve as an important community resource, not only for determining current observing strategies but also for planning future EM surveys. The research group will also place direct, observational constraints on the role of mergers in populating the Universe with heavy elements, by determining independently-measured ejecta masses and event rates. The researchers will build a complete census of SGRB host galaxies and the spatial offsets of bursts from the galaxy centers. From these observations, the researchers will determine the distributions of merger kick velocities and delay times. These distributions are vital inputs for binary evolution models, yet they are highly uncertain. The project is well-designed to exploit both methods of merger discovery: gravitational wave emission from Advanced LIGO/Virgo and gamma-ray burst detection from space-based missions. For all objectives in this proposal, the research group will make crucial connections between the local population of compact object mergers discovered by Advanced LIGO/Virgo and their cosmological analogues.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.