Physics Colloquium: Formed too Fast: Massive Galaxies at Cosmic Dawn
TUESDAY, November 14, 2023
3:30 PM PST
Refreshments at 3:15
Formed too Fast: Massive Galaxies at Cosmic Dawn
Caitlin Casey, The University of Texas at Austin
The pace of galaxy growth in the early Universe offers one of the strongest and most accessible tests of the Lambda-CDM cosmological framework. 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. Unusually bright high-redshift galaxies discovered by JWST challenge our most fundamental models of how fast stars form. 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, which would impact the timescale and uniformity of reionization — the last major phase change of the Universe from a neutral to ionized medium. I will present an overview of large, multi-wavelength observational campaigns I am leading 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 together with ALMA and Keck to work towards the goal of definitively establishing the story of how and when the first galaxies assembled.