Unraveling the galaxy assembly and AGN activity in a massive node of the Cosmic Web at z~3
Galaxies form and evolve within the densest structures of the Universe where they are fed by filamentary inflows of gas from the Cosmic Web. However, the processes regulating how galaxies accrete their gas and how this affects their gas content and AGN activity are still largely unknown. A recent VLT/MUSE survey around a z~3 quasar finally provided us with one of the first images of contiguous cosmic filaments on Mpc-scales converging into a node containing a large concentration of galaxies and AGN. This represents a perfect laboratory to investigate how is the role of large-scale environment on the galaxy formation and AGN activity at high-z. In this talk I will present recent ALMA follow-up observations toward this massive node of the Cosmic Web. Our observations targeting CO emission lines as well as mm-dust continuum allowed us to obtain a complete census of star-forming galaxies in the field, constraint the galaxy ISM properties, and reveal the morphology and kinematics of the cold gas component of galaxies and AGN embedded in the Cosmic Web node. I will discuss how these observations, in conjunction with multiwavelength data from NIR to X-rays, shed light on the assembly of galaxies and AGN activity in dense environments.