LEAPS-MPS: Constraining Supernova Explosion Models by Alpha Elements in Metal Poor Galaxies and the Intracluster Medium

一旦宇宙冷却到足以形成中性原子（大爆炸后约378，000年），其初始化学成分仅限于氢，氦和锂。元素周期表中的其他元素对从行星到生命的一切都是必要的，这些元素都是在随后的140亿年里在恒星中形成的，无论是在它们的一生中还是在它们作为超新星（SNe）的灾难性自我毁灭中，后者分散了新形成的元素。这些产物可以通过SNe残骸和恒星的光谱学直接观察到，以及填充在恒星（星际介质; ISM）和星系团（团内介质; ICM）之间空间的气体，并限制了宇宙中富集的历史。最近对贫金属星系以及英仙座星系团ICM的观测发现，在核心坍缩（II型）SNe中合成的α元素丰度之间存在系统性的不匹配（即，O、Ne、Si、S、Ar和Ca）和模型预测。首席研究员（PI）将领导一个本科研究团队，以确定导致这种不匹配的物理过程，并开发一系列新的SNe模型，以更好地解释观察到的丰度模式。该项目将招募代表性不足的学生参加研究实习PI和他的团队将开发一个SNe模型“管道”，其中包括（1）一个先进的恒星演化代码，用于计算一系列大质量星星模型，直到核心坍缩开始，（2）模拟爆炸阶段的一维和多维流体动力学代码，以及（3）后处理核合成。该团队将探索模型参数（如混合，爆炸能量和反应速率）对α元素产生的影响，并使用观测数据对这些参数进行约束。他们将选择可以很好地再现化学丰度的参数集，并将其用作生成具有各种参数的化学产率的恒星模型目录的基础，例如祖质量和金属丰度。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。

Once the universe cooled sufficiently for neutral atoms to form (~378,000 years after the Big Bang), its initial chemical composition was limited to hydrogen, helium, and lithium. The other elements in the periodic table necessary for everything from planets to life were all forged over the subsequent 14-billion years in stars, both during their lifetimes and in their cataclysmic self- destruction as supernovae (SNe), with the latter dispersing the newly formed elements. These products can be observed directly via spectroscopy of SNe remnants and stars, as well as the gas filling the space between stars (interstellar medium; ISM) and cluster galaxies (intracluster medium; ICM), and constrain the history of enrichment in the universe. Recent observations of metal poor galaxies, as well as the Perseus cluster ICM, find systematic mismatches between the abundances of alpha elements synthesized in core-collapse (Type II) SNe (i.e., O, Ne, Si, S, Ar, and Ca) and model predictions. The principal investigator (PI) will lead a team of undergraduate researchers to identify the physical processes responsible for this mismatch and develop a new series of SNe models to better account for the observed abundance patterns. The project will recruit underrepresented students for participation in research internships (six per year) and a summer program, as well as enabling public science talks by the PI.The PI and his team will develop a SNe model "pipeline" that includes (1) an advanced stellar evolution code for computing a sequence of massive star models up to the onset of core-collapse, (2) 1-D and multi-dimensional hydrodynamics codes for modeling the explosion phase, and (3) post-processing nucleosynthesis. The team will explore the effects of model parameters such as mixing, explosion energy, and reaction rates, on the production of alpha-elements and use observational data to place constraints on these parameters. They will select the parameter set where the chemical abundances can be well reproduced and use it as a basis to generate a catalogue of stellar models with chemical yields of various parameters, such as the progenitor mass and metallicity. They will also maintain a library of numerical SNe to help astronomers identify the origin of SNe identified by future observatories.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.