2023-04-11 - 2023-04-14
Caroline Heneka
Heidelberg University
The cosmic 21cm background, generated by the forbidden spin-flip transition of neutral hydrogen, tomographically maps up to 80% of the observable Universe. It follows cosmic structure formation from high redshifts of Cosmic Dawn (CD) and the Epoch of Reionization (EoR), just a couple of hundred million years after the Big Bang, until present cosmic times; think thousands of Cosmic Microwave Background measurements. In this lecture I will give an introduction to the 21cm background, its theoretical foundations and its application as a probe of astrophysics, cosmology and fundamental physics. We will have a look at the high redshift Universe in particular, when the first ionising sources formed during CD and when the EoR marks the Universe’s last big phase transition. Current and upcoming measurements of the 21cm signal are thus revolutionising our view of the Universe; prominent experiments are the SKA and its already data-taking precursors such as LOFAR, HERA and MWA. I will introduce the basics of interferometric and global 21cm radio observations as well as modern machine learning methods that are developed to deal with data rates unprecedented in astronomy.
