ITP |
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Teilchentee SS 2024
Seminar at the Institute for Theoretical Physics, Heidelberg University
Thursdays at 16:15 in Room 106 Philosophenweg 12
Before each seminar, the speaker gives an informal pre-talk, introducing the MSc and PhD students at the ITP to the broader context of the topic of the seminar.
Pre-talks start at 15:30.
Organizers: Caroline Heneka, Aleksas Mazeliauskas, Ayodele Ore
Date: 18.04.24
Speaker: Sarah Bosman (ITP)
Title: Hydrogen reionisation ends at z=5.3: what we know from quasar absorption spectroscopy
Abstract
Primordial hydrogen eventually becomes ionised under the effect of the first sources: primordial galaxies and potentially active galactic nuclei. The quest to understand the timing and morphology of reionisation is driving enormous efforts across both theory and instrumentation as cosmologists prepare to detect neutral hydrogen directly through the 21 cm signal. At the same time, our knowledge of the ending of reionisation has transformed over the last decade owing to the explosion of quasar spectroscopy of z>5. Analyses of the Lyman-alpha forest, and other absorption features, have uncovered consistent evidence for a late end to hydrogen reionisation at z<6. In this talk I will review this evidence, showing how the homogenisation of the ultra-violet background, the temperature of the intergalactic medium, and the mean free path of ionising photons all converge to a picture of reionisation ending at z~5.3. I will present broad implications for the sources powering reionisation, and discuss current open questions in the field of reionisation modeling.
