ASTRONOMY COLLOQUIUM

A growing number of surprisingly massive galaxies are now being found in the first billion years after the Big Bang that push the limits of theoretical predictions within Lambda-CDM. Unusually bright high-redshift galaxies discovered by JWST challenge our most fundamental models of how fast stars form. Some of them contain overly massive black holes whose formation is uncharted. Massive dusty starbursts found with ALMA are requiring new explanations about early dust production. The spatial distribution of massive galaxies within large scale structure may be more highly clustered than expected. I will present an overview of large, multi-wavelength observational campaigns to place the first comprehensive constraints on the rarest, most massive galaxies to emerge at z>6 and the impact they in turn have on our interpretations of the early Universe. These efforts unite the unprecedented sensitivity of JWST, ALMA, and Keck to work towards the goal of definitively establishing the story of how and when the first galaxies assembled.