CDS&E: A Bayesian Approach to Detecting the Cosmological 21 cm Epoch of Reionization Signal

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Observations of the cosmic dawn, when the first stars and galaxies formed, are exceedingly challenging, but essential to map the distribution and evolution of structures during this critical period. This project will develop a new technique for studying the properties of these first luminous objects. Extracting information from the data requires precision control of systematic errors and detailed accounting of uncertainties. Cosmic dawn and the associated Epoch of Reionization (EoR), when intergalactic hydrogen was re-ionized by energetic photons from the first luminous sources, are critical turning points in the universe's history. Compared to existing analyses, this work will more clearly distinguish real signals from systematic errors, and should provide an order of magnitude improvement in sensitivity and correspondingly improved constraints on the astrophysics occurring at that time.This award will support the development of interactive, publicly available, online pedagogical resources for training new students in 21 cm cosmology. The resources will consist of five to six short video lectures covering key introductory topics in radio interferometry and 21 cm cosmology. Each video will be accompanied by an interactive exercise using online software developed by the PI. This award will also support the continuation of the Research Experiences for Non-Traditional Undergraduates (RENTU) program at Brown University, which provides in-depth research experiences to non-traditional students, including first-generation college students, veterans, and other resumed-education undergraduates, working closely with them on a case-by-case basis.The planned methods rely on observations of the faint 21 cm line of neutral hydrogen at cosmic distances. This work will incorporate critical new capabilities in a Bayesian analysis pipeline with the level of rigor needed to maximize the scientific returns. The analysis will be applied to data from the Hydrogen Epoch of Reionization Array (HERA) and the Murchison Widefield Array (MWA) to produce stringent new limits on the 21 cm signal and yield new constraints on the physics of the cosmic dawn. This is particularly important for understanding the transition from the simple, homogenous early universe revealed by the cosmic microwave background, to the current universe, filled with galaxies, stars, and planets.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.