Bridging the Gap: Resolving Galaxy Assembly Across Cosmic Time with ALMA and JWST

A decade ago, studying gas, dust, and stars on resolved scales was limited to nearby galaxies. Thanks to groundbreaking observations with ALMA and JWST, we can now extend these studies to normal, main-sequence galaxies at the dawn of the Universe, when it was only 1 billion years old. In this talk, I will present exciting results from the CRISTAL ALMA Large Program (www.cristal.udec.cl), which, for the first time, leverages the combined power of ALMA, JWST, and HST to spatially resolve gas, dust, and stars in a large sample of star-forming galaxies at z = 4−6 on kiloparsec scales. The achieved physical resolution corresponds to the Jeans length in high-redshift, gas-rich galaxies—similar to the 100 pc Jeans length we resolve in nearby galaxies, offering for the first time a direct connection between the physical processes in normal, main-sequence galaxies near and far. By studying star formation (both obscured and unobscured), dust and metal content, ISM properties, kinematics, feedback, and outflows in this early cosmic epoch, we have obtained new perspectives on how galaxies assembled and evolved. These results provide a unique opportunity to connect galaxy assembly across cosmic time, bridging our understanding of both distant and nearby galaxies, and directly addressing the main scientific goals of the workshop, including galaxy assembly, star formation and feedback, and their impact on local and global scales.