WoU-MMA: Collaborative Research: Combining Theory with Observations to Unlock the Multi-Messenger Physics of Compact Binary Mergers

伴随伽马射线短暴的中子星星合并双星GW 170817的引力波和电磁辐射的探测，预示着多信使天体物理学的新时代的到来。对所有波长的GWs和光的综合分析使我们能够绘制出两个NS之间宇宙碰撞的非常详细的图像，解决了重元素起源之谜，证实了紧凑的双星合并和短GRB之间的联系，对相对论性喷流的物理学提出了新的见解，并为宇宙学提供了新的约束。然而，到目前为止只有一个事件，几个关键问题仍然悬而未决。 俄勒冈州州立大学（OSU）和德克萨斯理工大学（TTU）之间的科学合作将通过理论和观察研究相结合来调查几个主要的科学问题。天文学家还不知道GW 170817是一个典型的NS-NS合并，还是一个特殊的瞬变。必须研究更大样本的NS-NS合并的多样性，以便得出有关物理学的统计上有意义的结论。此外，一类新的瞬态所产生的合并黑洞（BH）与NS尚未研究。两名研究生和六名以上的本科生将在OSU和TTU接受研究培训。这两所学校的学生主要是第一代学生和来自当地农村社区的学生。共同主要研究者（PI）将通过与俄勒冈州科学与工业博物馆的合作伙伴关系，为公众带来适合年龄的演讲和动手活动。TTU将举办一个西班牙语讲座，由OSU共同PI提供。该项目有三个主要目标，将在宽带数据的限制下，通过开发和比较具体的逐事件模型来实现：（BH vs NS），以及在其相对论流出中起作用的加速机制，通过绘制GW和EM排放之间的时间延迟和喷出物角度结构的多样性;（ii）通过比较不同合并周围环境介质的性质，揭示NS-NS双星演化模型;（iii）通过比较NS-NS事件和NS-BH事件，表征合并动力学和NS性质（磁化和状态方程）的变化。俄勒冈州立大学小组已经开发了一套工具，用于相对论性喷流电磁辐射的数值模拟。TTU小组享有各种已经批准的观测计划，用于全球变暖的EM跟踪。通过这个OSU-TTU合作项目，模型预测将真实的反馈给观测者，最大限度地提高理论理解，同时最大限度地降低观测资源的成本。该项目推进了NSF宇宙大创意窗口的目标。该奖项反映了NSF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 detection of gravitational waves (GWs) and electromagnetic (EM) radiation from the binary neutron star (NS) merger GW170817, associated with a short gamma-ray burst (GRB), has heralded the new era of multi-messenger astrophysics. The combined analysis of GWs and light at all wavelengths has enabled us to draw a remarkably detailed picture of a cosmic collision between two NSs, solving the riddle of the origin of heavy elements, confirming the link between compact binary mergers and short GRBs, shedding new light on the physics of relativistic jets, and providing new constraints on cosmology. With only one event so far, however, several key questions remain open. A scientific collaboration between Oregon State University (OSU) and Texas Tech University (TTU) will investigate several major scientific issues through a combination of theoretical and observational research. Astronomers do not yet know whether GW170817 is a typical NS-NS merger, or rather a peculiar transient. The diversity of a larger sample of NS-NS mergers must be studied in order to derive statistically meaningful conclusions about the physics involved. Moreover, a new class of transients arising from mergers of black holes (BHs) with NSs is yet to be studied. Two graduate students and more than six undergraduate students will be trained in research at OSU and TTU. Both of these institutions have student populations dominated by first generation students, and students from local rural communities. The co-principal investigators (PIs) will bring age-appropriate presentations and hands-on activities to the public through partnerships with the Oregon Museum of Science and Industry. TTU will host a prize lecture in the Spanish language, to be delivered by the OSU co-PI. The project has three main goals that will be accomplished by developing and comparing specific event-by-event models, constrained by broad-band data: (i) determining the nature of merger remnants (BH vs NS), as well as the acceleration mechanisms at play in their relativistic outflows, by mapping the diversity of time delays between the GW and EM emissions, and of ejecta angular structures; (ii) shedding light on NS-NS binary evolution models by comparing the properties of the ambient medium around different mergers; (iii) characterizing the variety of merger dynamics and NS properties (magnetization and equation of state) by comparing NS-NS events and NS-BH ones. The OSU group has developed a suite of tools for numerical modelling of EM emission from relativistic jets. The TTU group enjoys access to a variety of already approved observing programs for EM follow-up of GWs. Via this OSU-TTU collaborative project, model predictions will be fed back to the observers in real time, maximizing theoretical understanding while minimizing costs in terms of observational resources. This project advances the goals of the NSF Windows on the Universe 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.