Collaborative Research: Petascale Simulations of Binary Neutron Star Mergers

随着激光干涉仪引力波天文台（LIGO）对两颗中子星（NSs）碰撞的非凡探测，以及随后通过x射线、光学、红外和无线电设备的观测，多信使天文学时代已经开始。这些观察已经开始彻底改变我们对物理学许多领域的理解，包括重元素的起源，如银、金和铂。然而，它们也提出了许多紧迫的悬而未决的问题。这个项目将利用蓝水超级计算机来解决这些悬而未决的问题。最先进的NS合并模拟将在Blue Waters超级计算机上进行，以检查所有不同可能的NS碰撞场景，以了解产生观测数据的基本物理过程。随后将进行高分辨率的模拟，考虑到合并后的演变。模拟结果将公开，并计划通过电影、公开讲座和学校访问进行传播。系统地研究与观测到的NS碰撞GW170817兼容的NS双星系统的演化，将通过在Blue Waters上进行合并模拟，采用复杂的微物理和中微子处理。这些模拟将确定潮汐扭矩和冲击作为合并过程中物质抛射机制的可行性，这反过来又为观测到的光学和红外瞬变提供动力，并合成重元素。将通过考虑一组跨越当前核不确定性范围的3个状态方程来评估NS状态方程（EOS）的影响。将评估合并的可能结果范围作为二元参数和EOSs的函数。将对合并残余物进行高分辨率的广义相对论磁流体动力学模拟，在对NS物质进行微物理处理的同时，具有足够的分辨率来确定磁旋不稳定性（MRI）和残余物中的角动量再分配。这些模拟结果将确定磁流体动力学过程在确定残骸寿命和早期或延迟黑洞形成的观测特征方面的作用。磁化风在光学和红外发射及其核合成产量中的作用将被评估。此外，该项目将对当前开源代码进行重大改进，所有改进将向社区发布。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 era of multimessenger astronomy has been inaugurated with the extraordinary detection of the collision of two neutron stars (NSs) by the Laser Interferometer Gravitational-Wave Observatory (LIGO), and the subsequent observations by X-ray, optical, infrared, and radio facilities. These observations have started to revolutionize our understanding of many areas in physics, including the origins of the heavy elements, like silver, gold, and platinum. However, they also pose many pressing open questions. This project will make use of the Blue Waters supercomputer to address these open questions. State-of-the-art NS merger simulations will be performed on the Blue Waters supercomputer to examine all the different possible NS collision scenarios to understand the fundamental physical processes that generated the observation data. This will be followed by extremely high-resolution simulations considering the post-merger evolution. Simulation results will be made publicly available, and dissemination via movies, public lectures and school visits are planned.A systematic study of the evolution of NS binary systems compatible with the observed NS collision, GW170817, will be performed by means of merger simulations on Blue Waters, employing sophisticated microphysics and neutrino treatment. These simulations will ascertain the viability of tidal torques and shocks as mechanisms for the ejection of matter during mergers, which in turn powers the observed optical and infrared transients and synthesizes heavy elements. The impact of the NS equation of state (EOS) will be evaluated by considering a set of 3 EOSs spanning the range of the current nuclear uncertainties. The range of possible outcomes of the merger as a function of the binary parameters and EOSs will be assessed. High-resolution general-relativistic magnetohydrodynamics simulations of the merger remnant will be performed, with sufficient resolution to determine the magnetorotational instability (MRI) and the angular-momentum redistribution in the remnant while employing a microphysical treatment of the NS matter. These simulation results will ascertain the role of magnetohydrodynamics processes in determining the lifetime of the remnant and the observational signatures of an early or delayed black-hole formation. The role played by magnetized winds in the powering of the optical and infrared emissions and their nucleosynthetic yields will be assessed. In addition, this project will develop significant improvements to current open-source codes, and all improvements will be released to the community.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.