Title: Illuminating the Cosmic Web and the Circumgalactic Medium with the Help of Quasars

Speaker: Sebastiano Cantalupo (Professor,the University of Milan Bicocca)

Time: 9:00am, April 16, 2024

Location: 3-302, PMO Xianlin Campus

Abstract: Our standard cosmological model predicts that most of the matter in the universe is distributed into a network of filaments - the Cosmic Web - in which galaxies form and evolve. Because most of this material is too diffuse to form stars, its direct detection in emission has remained elusive for several decades leaving fundamental questions still open, including: How are galaxies linked to each other? What are the morphological, physical and kinematical properties of the Cosmic Web and Circumgalactic gas on both large and small scales? How do they affect galaxy formation and evolution? During the last few years we have been able to start addressing these questions in a completely new way: i.e., by directly detecting intergalactic gas in emission thanks to “cosmic flashlights” such as quasars which can ionise and thus light-up through fluorescent emission cosmic gas over large volumes. Recent surveys exploiting the capabilities of new instruments such MUSE and KCWI are now providing a large statistical sample of three-dimensional images of rest-frame-UV line emission from “cold” gas haloes (and sometimes filaments) around galaxies, which are ubiquitously detected in the surrounding of quasars at all explored redshifts (2