Core-Collapse Supernovae Through Cosmic Time

当大质量恒星（那些质量至少是太阳8倍的恒星）到达它们存在的尽头时，它们会爆炸，释放出大量的重元素，这些重元素丰富了下一代恒星。对这些核心坍缩超新星及其喷发物进行建模需要在大型计算机上运行复杂且分辨率高的三维数值模拟。重元素（天文学家称之为“金属”）的丰度已经从大爆炸后形成的第一批恒星中没有元素增加到附近宇宙中最近形成的恒星中发现的类似太阳的成分。超新星取决于恒星爆炸前的结构，而爆炸前的结构又取决于恒星的质量和恒星中“金属”的含量。为了涵盖宇宙时间在超新星爆炸的恒星中的变化，我们将计算三个分辨率很高的3D超新星模拟，分别是低质量、中等质量和高质量的爆炸恒星，它们的三种“金属丰度”分别代表重元素从原始的零金属丰度到太阳金属丰度的积累。从这些模拟中，研究人员将提取爆炸及其喷射物的特性，以更好地了解超新星机制的本质及其在宇宙时间中对星系演化的贡献。研究人员将使用他们的多物理场Chimera代码，其中包括具有现代中微子物质相互作用的中微子辐射流体动力学，对多极自引力的广义相对论修正，致密物质核状态方程和内置核网络，以计算铁核外非平衡层和喷射物中的演化丰度。在类似的二维（轴对称）模拟中，将对低（约10个太阳质量）、中（约15个太阳质量）和高（约25个太阳质量）祖细胞的每种金属丰度进行1度分辨率的模拟计算。模拟将在零、太阳和低金属丰度下进行计算，并将计算喷射物的直接和后处理核合成。进一步的分析将产生引力波和中微子信号，直接探测中央超新星引擎。

When massive stars (those with at least 8 times the Sun's mass) reach the end of their existence they can explode releasing large quantities of heavy elements that enrich the next generation of stars. Modeling these core-collapse supernovae and their ejecta requires complex and well resolved three-dimensional numerical simulations running on large computers. The abundances of heavy elements (known as 'metals' to astronomers) has increased from none in the very first stars formed after the Big Bang to the Solar-like composition found in recently formed stars in the nearby universe. Supernovae are dependent on the pre-explosion structure of the star, which is dependent on both the stellar mass and the amount of 'metals' in the star. To cover the variation through cosmic time in the stars that explode as supernovae we will compute three well-resolved 3D supernova simulations for low, medium, and high mass exploding stars at each of three 'metallicities' representing the build-up of heavy elements from the primordial zero metallicity to solar metallicity. From these simulations the investigators will extract the properties of the explosions and their ejecta to get a better understanding of the nature of the supernova mechanism and its contributions to the evolution of galaxies through cosmic time.The investigators will use their multi-physics Chimera code, which includes neutrino radiation hydrodynamics with modern neutrino-matter interactions, general relativistic corrections to multi-pole self-gravity, a dense matter nuclear equation of state, and built-in nuclear networks to compute evolving abundances in the non-equilibrium layers outside the iron-core and in the ejecta. The three simulations of 1-degree resolution will be computed at each metallicity from low (about 10 solar mass), medium (15 solar mass), and high (about 25 solar mass) progenitors found to explode in similar 2D (axisymmetric) simulations. Simulations will be computed at zero, solar, and low metallicities and both direct and post-processed nucleosynthesis will be computed for the ejecta. Additional analyses will produce gravitational wave and neutrino signals that directly probe the central supernova engine.