Speaker
Description
The Lyman-alpha (Lya) emission line is a powerful tool for studying the circumgalactic medium (CGM) of high redshift galaxies. Large-scale gas flows induced by feedback as well as accretion from intergalactic medium (IGM), mediated by resonant scattering at HI gas, imprint themselves through the skewed spectral shape of the line, which is shifted redwards from systemic velocity. Recent observations revealed for the first time a trend at large radii (r >~ 15 kpc, or ~0.5 R_vir) that the "red peak" of the line shifts back towards systemic and possibly even beyond - a trend not previously predicted by models. This phenomenon could mark the importance of inflows to shape the outer CGM of high-z galaxies, enriching it with the cold gas and competing with the strong outflows that presumably dominate the inner circumgalactic regions. We present the first analysis of this phenomenon for a large sample of Lya emitters using exquisit observing data with MUSE obtained in various Deep Fields. We map the Lya profile out to very large radii, in particular characterising the peak shift behaviour, and link this to the nature of the underlying gas flows and CGM properties.