Elements: An initial value solver for the era of multi-messenger astrophysics

“多信使”天文学的出现有望解决一些长期存在的天体物理学难题，如短伽马射线爆发和r过程元素的起源，以及超核密度物质的性质。正如事件GW 170817已经确定的那样，这些现象发生的地点是双中子星和/或黑洞-中子星的合并。对于任何广义相对论模拟来说，最基本的是构造初始值，这些初始值将演化并描述在初始时刻所考虑的天体物理系统。该奖项支持社区开源的广义相对论初值代码的开发，该代码在多信使天文学时代非常有用。新的代码将基于私有的紧凑对象计算器代码，重点是为天体物理学社区提供目前无法使用的现代和准确的建模工具。这个模块系统将协同工作，使用户能够设置新的初始数据类型。将特别关注长期可持续性和与当前NSF支持的网络基础设施的互连性。该基金支持的研究和推广活动有助于在各级教育中推广计算机的使用，以及公众对引力物理学和天体物理学最新和最令人兴奋的发展的认识。该基金的重点是建立孤立或双星系统中强引力磁化致密物体的模型。除了数值模拟，该计划还涉及在广义相对论，相对论流体力学和磁流体力学等天体物理学相关系统的分析处理。与此同时，将开发必要的基础设施，将新的初始数据与目前使用的各种进化代码（在某些情况下由NSF资助）连接起来。将编制大量文件，降低这一领域新研究人员的准入门槛。随着更灵敏的引力波探测器--如NSF领导的LIGO Voyager将提供对中子星和恒星质量黑洞的精细观测，或丽莎将瞄准超大质量黑洞--投入使用，对强引力多信使源进行更真实和准确的建模将变得势在必行。为这种建模提供工具是该奖项的动机。该项目推进了“宇宙之窗：多信使天体物理学时代”的目标，这是NSF未来投资的十大想法之一。该奖项由高级网络基础设施办公室（Office of Advanced Cyberinfrastructure）颁发，由数学和物理科学理事会（Directorate for Mathematical and Physical Sciences）物理部（Division of Physics）信息前沿物理学项目（Physics at the Information Frontier program）共同支持。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 advent of "multimessenger” astronomy promises to resolve a number of long-standing astrophysical puzzles, such as the origin of short gamma-ray bursts and r-process elements, as well as the nature of matter at supranuclear densities. As already established by event GW170817, the sites where these phenomena take place are mergers of binary neutron stars, and/or black hole--neutron stars. Essential to any general relativistic simulation is the construction of the initial values that will be evolved and which describe the astrophysical system under consideration at an initial moment. This award supports the development of a community open source, general relativistic initial value code useful in the era of multimessenger astronomy. The new code, which will be based on the private Compact Object CALculator code will focus on providing to the astrophysics community modern and accurate modeling tools that are currently not available to them. This system of modules will work together and give users the capability to set up new initial data types. Special attention will be paid to long term sustainability and interconnectivity with current NSF supported cyberinfrastructure. The research and outreach activities supported by this grant help promote the use of computers at all levels of education, as well as the public awareness of some of the latest and most exciting developments in gravitational physics and astrophysics.Modeling of strongly gravitating magnetized compact objects either in isolation or in a binary system is the focus of this award. In addition to numerical modeling, this program involves also analytical treatment of such astrophysically relevant systems in general relativity, relativistic hydrodynamics and magnetohydrodynamics. At the same time the necessary infrastructure to connect the new initial data with a variety of evolution codes that are currently used (and in some cases funded by the NSF), will be developed. Extensive documentation will be produced that will lower the entrance barrier of new researchers in this field. As more sensitive gravitational wave detectors ---such as the NSF-led LIGO Voyager that will provide exquisite observations of neutron stars and stellar mass black holes, or LISA that will target supermassive black holes--- come into operation, the necessity for more realistic and accurate modeling of strongly gravitating multimessenger sources will become imperative. Providing a tool for such modeling is the motivation for this award.This project advances the objectives of "Windows on the Universe: the Era of Multi-Messenger Astrophysics", one of the 10 Big Ideas for Future NSF Investments. The award by the Office of Advanced Cyberinfrastructure is jointly supported by the Physics at the Information Frontier program in the Division of Physics within the Directorate for Mathematical and Physical Sciences.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.