Dr. Joshua S. Dillon; University of California, Berkeley
21 cm cosmology promises to become a revolutionary new 3D probe of our universe. With it, we can uncover the astrophysics of the "Cosmic Dawn"—the era of the first stars and galaxies—and test our standard model of cosmology with exquisite precision. Realizing the potential of 21 cm cosmology requires overcoming considerable challenges; the 21 cm signal from neutral hydrogen is buried under astrophysical foregrounds that are orders of magnitude brighter. We will need to carefully calibrate and analyze vast quantities of data from large radio interferometers. In this talk, I will present results from the Hydrogen Epoch of Reionization Array (HERA), a purpose-built 21 cm experiment being commissioned in South Africa. I will show how HERA is already setting the most sensitive upper limits on the 21 cm reionization power spectrum to date with just a fraction of its design sensitivity and how those limits are now informing our models of reionization. Finally, I will lay out a vision for how HERA and the analysis techniques we've developed point the way forward for the next generation of telescopes that will directly map the majority of the luminous matter in the universe.