Differentiating Electron-Capture and Core-Collapse Supernovae

核心坍缩超新星标志着大质量恒星的死亡以及中子星和黑洞的形成。它们的名字就是由此而来的，除了它们的视觉表现之外，它们还以释放出大量的中微子和向它们的星系喷射出数量惊人的新形成的原子核为标志。事实上，是中微子流驱动了爆炸。我们这个星球和我们自己的大部分化学成分最初都来自这些爆炸，因此，核心坍缩超新星是我们起源链上必不可少的一环。有了这个项目，对中子星形成、中微子发射和新原子核形成的最先进的模拟将延长到几个小时到几天后，当这些新形成的元素被望远镜观测到的时候。与此同时，最先进的超新星模型将扩展到不太常见、研究不太充分的电子捕获超新星，这种超新星发生在质量稍小的超级渐近巨星分支恒星中。在此过程中，两名研究生将接受核天体物理学和计算科学方面的培训，为他们毕业后加入STEM工作岗位做好准备。这个项目将产生世界领先的模拟核心坍缩和电子捕获超新星的能力，计算它们的核合成，并将这些预测与超新星、超新星遗迹和星系化学演化的观测结果进行比较。在CHIMERA代码中包含任意核反应网络对于这些研究来说是一个显著的优势。对于捕获电子的超新星来说，包含几百种核物质的过程正在进行中，这使得引发爆炸的电子捕获比以前可能的更完整。在CHIMERA中，核心坍缩超新星已经证明了160种核物质的包含，为迄今为止核心坍缩超新星的多维模型提供了最广泛的核组成代表。核心坍缩和电子捕获模拟的扩展，以及它们对核组成的详细描述，通过整个恒星包层进入星周介质，直到喷出物达到同质性，打开了在爆炸后几天到几个月的光子观测来约束这些模型的可能性，因为元素的组成和分布在这些观测中起着至关重要的作用。因此，这些模型将阐明我们目前对超新星核合成的理解中的缺陷。该项目推进了“宇宙之窗：多信使天体物理学时代”的目标，这是美国国家科学基金会未来投资的十大理念之一。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。

Core-collapse supernovae mark the deaths of massive stars and the formation of neutron stars and black holes. Beyond the visual display from which they draw their name, they are also marked by the release of tremendous fluxes of neutrinos and the ejection into their galaxy of prodigious quantities of newly made atomic nuclei. In fact, it is the neutrino flux which powers the explosion. Much of the chemical composition of our planet and ourselves comes originally from these explosions, thus core-collapse supernovae are an essential link in our chain of origins. With this project, state-of-the-art simulations of the formation of the neutron star, the emission of the neutrinos and the formation of new atomic nuclei will be extended to the epoch, hours to days later, when these newly made elements become visible to telescopic observations. In parallel, state-of-the-art models of supernovae will be extended to less common, less well studied, electron-capture supernovae, which occur in somewhat less massive, super Asymptotic Giant Branch stars. In the process, two graduate students will be trained in both nuclear astrophysics and computational science, equipping them to join the STEM workforce upon graduation.This project will result in a world-leading ability to simulate core-collapse and electron-capture supernovae, calculate their nucleosynthesis, and compare these predictions with observations of supernovae, supernova remnants and galactic chemical evolution. The inclusion in the CHIMERA code of arbitrary nuclear reaction networks is a significant advantage for these studies. For electron-capture supernovae, inclusion of a couple hundred nuclear species is underway, allowing for much more complete coverage of the electron captures that initiate the explosion than has previously been possible. Inclusion of 160 nuclear species has already been demonstrated in CHIMERA for core-collapse supernovae, providing the most extensive representation of the nuclear composition in a multi-dimensional model of a core collapse supernova to date. Extension of both core-collapse and electron capture simulations, with their detailed representation of the nuclear composition, through the entire stellar envelope and into the circumstellar medium until the ejecta achieves homology, opens the possibility to constrain these models with photonic observations from days to months after explosion, as the composition and distribution of the elements plays an essential role in these observations. Thus these models will shed light on the shortcomings in our current understanding of supernova nucleosynthesis.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.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.