Astrophysics Colloquium The Obscured Star Formation at High Redshift: The Birth of the Giants Presented by Matthieu Bethermin Laboratoire d'Astrophysique de Marseille Thursday, September 6, 2018 11:00 A.M. in 169-336 and on Webex Abstract The impressive progress of far-infrared and millimeter astronomy in the last decade allowed us to probe the star-formation hidden in the dust clouds way beyond z~2. It is now clear that very massive and dusty objects already exist at z~7. But, what is the exact contribution of these dusty objects to the global picture of galaxy evolution? I will discuss the current constraints on the star formation density that we can obtain at z>3 using indirect methods (modeling, CIB anisotropies) and present some on-going and future projects, which should address these questions. I will then discuss more specifically the nature of the high-z dusty star-forming galaxies. How can these systems host such impressive star formation. I will present the latest results obtained with ALMA to characterize their ISM (gas mass, dense gas fraction...). One of the main results of this study is the presence of incredibly large reservoirs of molecular gas. I will finally explain why it is not so surprising, considering the large mass of their host dark-matter halos. JPL Contact: Olivier Dore (4-0690)   Site Manager: Webmaster: CL 08-3220