Collaborative Research: A Better Measurement of the Primordial Helium Abundance

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 of primordial 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.