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

来自双中子星(NS)合并的GW170817引力波(GWS)和电磁辐射(EM)辐射的探测，伴随着一次短伽马射线暴(GRB)，预示着多信使天体物理的新时代。对所有波长的GW和光的联合分析使我们能够非常详细地描绘出两个NSS之间宇宙碰撞的非常详细的图景，解决了重元素起源的谜团，证实了致密的双星合并和短伽玛暴之间的联系，为相对论喷流的物理学提供了新的曙光，并为宇宙学提供了新的约束。然而，到目前为止只有一次活动，几个关键问题仍然悬而未决。俄勒冈州立大学(OSU)和德克萨斯理工大学(TTU)之间的一项科学合作将通过理论和观测研究相结合的方式来研究几个主要的科学问题。天文学家们还不知道GW170817是典型的NS-NS合并，还是更确切地说是一种特殊的瞬变。必须对NS-NS合并的更大样本的多样性进行研究，以便就所涉及的物理问题得出有统计意义的结论。此外，由黑洞(BHS)和NSS合并而产生的一类新的瞬变现象还有待研究。两名研究生和六名以上的本科生将在俄亥俄州立大学和TTU接受研究培训。这两所学校的学生群体以第一代学生为主，学生来自当地农村社区。联合首席调查员(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示和动手活动。TTU将主办一场西班牙语有奖讲座，由俄亥俄州立大学联合PI发表。该项目有三个主要目标，将通过开发和比较特定的逐个事件模型来实现，受宽带数据的限制：(I)确定合并残余物(BH与NS)的性质，以及在它们的相对论外流中发挥作用的加速机制，通过绘制GW和EM发射之间的时间延迟的多样性，以及抛射角结构的差异；(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；(3)通过比较NS-NS事件和NS-BH事件来表征合并动力学和NS性质(磁化和状态方程)的变化。OSU小组开发了一套工具，用于对相对论喷流的电磁发射进行数值模拟。TTU小组享有各种已经批准的GWS EM后续观察计划的使用权。通过这个OSU-TTU合作项目，模型预测将实时反馈给观测者，在最大限度地了解理论的同时，将观测资源的成本降至最低。这个项目推进了NSF宇宙大理想之窗的目标。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.