APEC Seminar (Astronomy - Particle Physics - Experimental Physics - Cosmology)

Speaker: Lutz Wisotzki (Leibniz-Institut für Astrophysik Potsdam (AIP))
Title: Faint high-redshift galaxies and their Lyman-alpha emission
Date: Thu, Apr 16, 2020, 16:00 - 17:00
Place: Zoom Seminar
Related File: 2512.pdf
Abstract: Many investigations of the high-redshift universe are still limited to the brighter and therefore more massive part of the galaxy population. I present observations with the MUSE instrument at the ESO-VLT that have enabled us to probe spectroscopically into the domain of genuine low-mass dwarf galaxies at z>3 through their Lyman-alpha emission. We find remarkable trends in spectral properties as a function of luminosity that may hold important clues about the contribution of faint galaxies to the cosmic UV radiation field, and thus to reionisation. Moreover, extended Ly-alpha emitting envelopes appear to be ubiquitous around even the faintest galaxies, revealing huge reservoirs of cold gas in the circumgalactic medium. At the sensitivity level reached by our data, the Ly-alpha emission cross-sections are comparable to those of high-column density hydrogen absorbers, suggesting that a large fraction of atomic hydrogen at these redshifts has now also been detected in emission. I discuss some implications for the demographics of high-redshift galaxies.