Understanding the Early Universe with 21 cm Cosmology: Progress, Challenges, and Next Steps
Measuring the 21 cm emission line from neutral hydrogen at high redshift has the potential to revolutionize our understanding of the universe's evolution and early galaxy formation. These measurements would provide 3-dimensional maps of the universe during the Dark Ages, Cosmic Dawn, and Epoch of Reionization, when stars and galaxies first formed and ionized the intergalactic medium. However, 21 cm cosmology experiments have not yet overcome the challenges that will allow them to achieve their potential. In particular, these experiments struggle to separate the faint cosmological signal from intervening foreground emission that is 4-5 orders of magnitude brighter. I discuss recent progress constraining the high redshift 21 cm signal and developing new techniques to improve the precision of these analyses.