Collaborative Research: EDGES-3: Validating and Refining Global 21cm Measurements of Cosmic Dawn

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Astronomers are searching for signs of the first stars and galaxies that formed in the universe. This period in cosmic history is called the Epoch of Reionization (EoR). The Experiment to Detect the Global EoR Signature (EDGES) is an ongoing project to study this early period. In 2018, EDGES reported the first-ever detection of evidence of light from the first stars. These stars where shining 180 million years after the Big Bang, when the universe was merely one percent of its current age. The EDGES project uses radio observations to probe the early universe. This project will build a new radio antenna and receiver for EDGES. The instrument will be used to confirm previously reported evidence. Students from the diverse community of Arizona State University will help to build the instrument and analyze its data. This experience will help to prepare them for future careers and give them a unique research opportunity.Observing the formation of the first stars, galaxies, and black holes over 13.5 billion years ago is the next frontier in observational cosmology. After the first stars formed, they produced a background of ultra-violet photons that affected the surrounding hydrogen gas, enabling the gas to be detected in absorption against the cosmic microwave background. In early 2018 this research team reported the first evidence for detection of this signal, but the amplitude was twice the predicted level and the timing of the signal was earlier than expected. This project will develop a new radio antenna and receiver that will improve on previous performance by a factor of three, enabling a verification of the previous detection and detailed characterization of the signal. The project will engage students from Arizona State University to build the instrument and analyze its data, preparing them for future careers. The research team will disseminate technical advances in radio instrumentation through technical memos and journal articles.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.