| Abstract: The peak in cosmic star formation rate density around redshift ~2 remains a puzzle till date. It is believed that gas accretion and galactic winds within the circumgalactic medium (CGM) hold the key. Studying the CGM of high-z, low-mass galaxies is particularly important, as their shallow potentials make them more susceptible to galactic-scale outflows, though detecting these faint systems has long been challenging. With MUSE enabling the detection of high-z galaxies via their Lya emission, our MUSE Quasar-field Blind Emitters Survey (MUSEQuBES), is dedicated to study the extended gaseous medium around 96 z=3.3 Lyman-alpha Emitters (LAEs) using bright background quasars. Voigt-profile fitting of absorption lines associated with these LAEs reveals that, unlike low-redshift systems, a substantial fraction of the associated CIV components are not gravitationally bound to their host halos. We also find enhanced gas and metal content around galaxies in group environments compared to isolated systems. Galaxies rich in neutral gas, identified through their rest-frame Lya equivalent widths, preferentially reside in gas-rich surroundings. Furthermore, photoionization modelling of the galaxy-associated absorbers with mini-halo-like overdensities reveals two distinct populations: a metal-poor component consistent with the diffuse intergalactic medium and a significantly metal-rich component, likely tracing enriched galactic gas. By combining emission and absorption diagnostics, we also report the direct detection of a cosmic web filament traced by an overdensity of LAEs, along with a giant Lya nebula that we argue is powered predominantly by in-situ recombination. As massive structures were still assembling, the identification of galaxy groups embedded in filamentary environments, together with indications of enhanced cool CGM gas in group environments, suggests a link between large-scale environment, gas availability, and the rise of star formation toward cosmic noon. |
