[Astronomy seminar] Astronomy Seminar on Friday 6 October

[Astronomy seminar announcements]

All,

The next Astronomy seminar will be:

*** Friday 6 of October from 10:30 to 11:30 at FC 61 ***

Welcome.


Title: Illuminating the Dark Universe with fluorescent Lyman-alpha emission

Speaker: Sebastiano Cantalupo, ETH Zürich

Abstract: Gravitational collapse during the Universe's first billion 
years transformed a nearly homogeneous matter distribution into a 
network of filaments - the Cosmic Web - where galaxies form and evolve. 
Because most of this material is too diffuse to form stars, its study 
has been limited so far to absorption probes against background sources. 
In this talk, I will present the results of a new program to directly 
detect and study high-redshift cosmic gas in emission using bright 
quasars and galaxies as external "sources of illumination’’. In 
particular, I will show results from ultra-deep narrow-band imaging and 
recent integral-field-spectroscopy as a part of the MUSE Guaranteed Time 
of Observation program that revealed numerous giant Lyman-alpha emitting 
filaments extending up to several hundred kpc around quasars and bright 
galaxies. I will discuss how the unexpectedly high luminosities of these 
systems, together with the constraints from Helium and metal extended 
emission, represent a challenge for our current understanding of 
cosmological structure formation. In particular, I will show that 
current observations suggest that a large amount of “cold" and dense 
gaseous “clumps" should be present around high-redshift galaxies and I 
will present our first attempts to understand the origin and nature of 
these structures using high-resolution hydrodynamical simulations.