Sebastiano Cantalupo

Direct imaging of the Dark Universe with the help of supermassive black-holes and Integral Field Spectroscopy

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 mostly limited so far to one-dimensional absorption probes against background sources or to three-dimensional studies limited however by relatively poor spatial resolution. In this talk, I will show how deep narrow-band imaging on Keck and Integral Field Spectroscopy with VLT/MUSE around bright quasars is providing us a completely new window for the study of the high-redshift Universe. In particular, using quasars and bright galaxies as external “sources of illumination”, we are now finally able to directly map in Ly-alpha emission and at high spatial resolution the diffuse gas that traces the sites of early galaxy formation (“dark galaxies”), the circumgalactic medium, as well as intergalactic filaments extending up to several hundred of kpc around massive galaxies. I will discuss the importance of the new instrumentation such as MUSE (and the Keck Cosmic Web Imager in the next future) for the tremendous discoveries and advancements in the last few years in this new field and I will present our first attempts to advance in parallel our physical understanding of baryonic structure formation as traced by the intergalactic Ly-alpha emission.