Speaker: Dr Sarah Bosman (ITP, Heidelberg)

Title: Cosmic reionisation: recent observational progress and challenges

Abstract: The ionisation of hydrogen in the intergalactic medium, thought to have occurred mainly around redshift 7 or 8, was a unique cosmological epoch when the first stars had a drastic impact on the Universe as a whole. Reionisation offers an opportunity to check the agreement between our understanding of large-scale structure formation and galaxy formation. In recent years, the end stages of reionisation have been studied in excellent detail with the Lyman-alpha forest, even providing a precise ending time for the process. However, this ending time is in tension with observations of the first galaxies by the James Webb Space Telescope, and some reionisation theorists are re-evaluating classical assumptions on the required "budget" of UV photons to complete reionisation. In this talk, I will review these recent breakthroughs and challenges.

Note: Sarah will be around on Wednesday afternoon. If you would like to meet with her, please let me know.

• Date:
  July 9, 2025, 11 a.m. – noon
  
  
• Location:

  AIP; Kirch building, Conference room

  
  
• Contact:
  Ewald Puchwein
  epuchwein@aip.de