Astronomy Colloquium
Apr
14
2026
Apr
14
2026
Description
New Probes of Astrophysics and Cosmology with 21cm cosmology
In recent years, considerable progress has been made in using the 21cm line of neutral hydrogen to survey the high-redshift universe. First, I will summarize recent new upper limits from the Hydrogen Epoch of Reionization Array (HERA). These limits are now strong enough that they rule out certain theory models of Cosmic Dawn (the era of first-generation stars and galaxies). Looking forward to future opportunities, I will describe ways in which Cosmic Microwave Background (CMB) measurements can be complementary to 21cm measurements, both on the technical side of making a measurement and in extending the science reach of either probe. In doing so, I will discuss some recent efforts to use symbolic regression as a tool for understanding the relationship between the wide variety of models of reionization in the literature. This enables critical evaluations of theory systematics in these models and how such systematics may propagate to joint CMB-21cm constraints.
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