Collaborative Research: Probing Dark Lights with Big Bang Nucleosynthesis and the Cosmic Microwave Background

这个奖项资助了伊利诺伊大学的布莱恩·菲尔兹教授和加州戴维斯大学的劳埃德·诺克斯教授的研究活动。大爆炸核合成理论（BBN）描述了在大爆炸的最初几秒钟内产生最轻的元素--氢、氦和锂。BBN对宇宙轻元素丰度的预测与观测结果基本一致;这种一致性是热大爆炸模型的一个重大成功。此外，BBN提供了宇宙中普通物质（“重子”）含量的量度，以及可见和不可见形式的相对论粒子（“辐射”）的总含量（例如，中微子和任何其他形式的“暗光”）。在过去的十年中，宇宙微波背景辐射（CMB）已经成为一种精确而独立的宇宙重子测量方法。BBN和CMB重子测度的比较为热大爆炸宇宙学提供了一个新的基本检验，并揭示了一个“锂问题”。“BBN/CMB连接现在准备打开质量上的新可能性。 最近和即将进行的CMB测量首次将同时探测不仅是宇宙重子，而且是宇宙辐射以及氦丰度本身。这将使强大的新宇宙学测试成为可能：第一次，BBN的预测可以完全用非常精确的CMB数据进行测试。一致性将戏剧性地证明标准宇宙学的一致性，而任何差异都将探索新的物理学。 教授领域和诺克斯都将评估和解释BBN-CMB比较，开发工具，以有效和准确地比较BBN和CMB数据。这是第一次，马尔可夫链蒙特卡罗方法将被用来评估BBN的不确定性;这将允许一个直接和一致的方法相结合的BBN预测和CMB数据和统计特征的结果。作为这项分析的一部分，一个新的开源BBN代码将被制作、测试和公开发布。预计这项工作将产生更广泛的影响。 一个公开的开源BBN代码将被发布。此外，CMB和早期宇宙粒子天体物理学界之间，以及粒子天体物理学、宇宙学和天文学学界之间将建立新的、强有力的联系。研究生，无论是在研究指导的正式课程，将接受培训，以综合这些方法，并在跨学科的方式工作。此外，教授。菲尔兹将保持积极、持续的外展计划，包括学校访问和公开讲座，将这一前沿科学带给更广泛的受众。

This award funds the research activities of Professor Brian Fields at the University of Illinois and Professor Lloyd Knox at the University of California Davis.The theory of big bang nucleosynthesis (BBN) describes the production of the lightest elements--hydrogen, helium, and lithium--in the first seconds of the big bang. BBN predictions for cosmic light-element abundances are in broad agreement with observations; this concordance is a major success of the hot big bang model. Moreover, BBN provides a measure of the ordinary matter ("baryon") content of the universe, as well as total content in relativistic particles ("radiation") in both visible and invisible form (e.g., neutrinos and any other forms of "dark light"). In the past decade, the cosmic microwave background (CMB) has emerged as a precise and independent measure of cosmic baryons. Comparing BBN and CMB baryon measures thus has provided a new fundamental test of the hot big bang cosmology, and reveal a "lithium problem." This BBN/CMB connection is now poised to open qualitatively new possibilities. Recent and upcoming measurements of the CMB for the first time will simultaneously probe not only cosmic baryons, but also cosmic radiation as well as the helium abundance itself. This will enable powerful new tests of cosmology: for the first time, the predictions of BBN can be tested entirely with very precise CMB data. Agreement would dramatically demonstrate the consistency of the standard cosmology, while any difference probes new physics. Professors Fields and Knox will both evaluate and interpret the BBN-CMB comparison, develop tools to efficiently and accurately compare BBN and CMB data. For the first time, a Markov-chain Monte Carlo approach will be used to evaluate BBN uncertainties; this will allow a direct and consistent means of combining BBN predictions and CMB data and statistically characterizing the results. As part of this analysis, a new open-source BBN code will be produced, tested, and publicly released.It is expected that this work will have substantial broader impacts. A publicly available open source BBN code will be released. Moreover, new and strong links will be forged among the CMB and early-universe particle astrophysics communities, and more widely among the particle astrophysics, cosmology, and astronomy communities. Graduate students, both in formal courses in research mentoring, will be trained to synthesize these approaches and to work in an interdisciplinary way. In addition, Profs. Fields will maintain vigorous, sustained outreach programs which include school visits and public lectures bringing this forefront science to a wider audience.