Collaborative Research: A Better Measurement of the Primordial Helium Abundance

在宇宙大爆炸后的五分钟内，在原始核合成过程中，宇宙中几乎所有的氦都产生了。原始氦的产生取决于当时宇宙的含量和相互作用。这使得对原始氦气量的精确测量对于测试新物理模型至关重要。明尼苏达大学、冈萨加大学和俄亥俄州立大学的科学家们通过对40多个贫金属矮星系的观测，将以前所未有的精度确定原始氦的丰度，为标准模型以外的新物理模型提供基本测试。这一计划将通过培养研究生、让本科生参与研究以及激发公众对科学的兴趣来产生更广泛的影响。该计划的公共宣传部分包括继续明尼苏达州的公园宇宙计划，利用俄亥俄州立大学阿恩·斯莱特巴克天文馆接触哥伦布的经济困难(和少数族裔占多数)的城市学校和俄亥俄州的许多农村学校，以及加强对科学在行动中的参与！在最近的几项投资和突破的基础上，现在有可能将原始氦丰度的观测不确定性降低到1%以下，这意味着中微子味道的数量的不确定度约为3%。大型双筒望远镜(LBT)上的多目标双谱仪(MODS)能够同时观测多条氢和氦复合线，这是高保真测量星云氦丰度所必需的。该计划将结合贫金属星系的LBT/MODS光谱和近红外光谱，并使用改进的、复杂的分析方法来确定单个目标的氦丰度，不确定度约为2%。通过对40多个贫金属星系的新观测，该团队将测量原始氦丰度的值，不确定度约为0.5%。该项目利用了最近发现的许多极度缺乏金属的星系，获得了使用大型望远镜的灵敏新仪器，以及日益复杂的丰度分析方法。对原始氦丰度的更高精度测量将对许多建议的模型扩展标准模型提供强有力的限制。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Within five minutes after the Big Bang, during primordial nucleosynthesis, almost all of the helium in the universe was produced. The production of that primordial helium depends on the content and interactions of the universe at that time. This makes a precise measurement of the amount ofprimordial helium of fundamental importance for testing models of new physics. Using observations of more than 40 metal-poor dwarf galaxies, this collaboration between scientists at the University of Minnesota, Gonzaga University, and The Ohio State University, will determine the primordial helium abundance with unprecedented precision, providing a fundamental test of models of new physics beyond the standard model. This program will have broader impacts through training graduate students, engaging undergraduates in research, and inspiring public interest in science. The public outreach components of this program consist of continuing the Universe in the Park program in the state of Minnesota, the use of the Ohio State University Arne Slettebak Planetarium to reach economically disadvantaged (and minority-majority) urban schools in Columbus and many rural schools in Ohio, and enhanced participation in the Science in Action! program for elementary school students in the Spokane, WA area, targeting schools with the most underserved and disadvantaged populations.Building on several recent investments and breakthroughs, it is now possible to reduce the observational uncertainty on the primordial helium abundance to below 1%, translating to an uncertainty of approximately 3% on the number of neutrino flavors. The Multi-Object Double Spectrographs (MODS) on the Large Binocular Telescope (LBT) enable the simultaneous observation of multiple hydrogen and helium recombination lines necessary for high-fidelity measurements of nebular helium abundances. This program will combine LBT/MODS spectra of metal-poor galaxies with near-infrared spectra and use an improved, sophisticated analysis methodology to determine helium abundances of individual targets with uncertainties of approximately 2%. With new observations of more than 40 metal-poor galaxies, the team will measure a value for the primordial helium abundance with an uncertainty of approximately 0.5%. This project takes advantage of the recent discoveries of many extremely metal-poor galaxies, access to sensitive new instruments on large telescopes, and increasingly sophisticated abundance analysis methodologies. A higher precision measurement of the primordial helium abundance will provide a strong constraint on many proposed models extending the standard model.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.