What Builds and Quenches the Most Massive Galaxies in the Early Universe?
Mengyuan Xiao, Longji Bing, Guilaine Lagache, Miroslava Dessauges-Zavadsky, Olivier Ilbert, Benjamin Magnelli, Pascal A. Oesch
TL;DR
The paper argues that understanding the formation and quenching of the most massive galaxies in the early universe requires a next-generation wide-field FIR/sub-mm facility. It proposes a ~50 m aperture telescope with wide sky coverage and high mapping speed to perform degree-scale rest-frame FIR surveys that detect both dusty and unobscured systems, linking dust and gas tracers to galaxy environments. It outlines three core science goals—measuring the true space density, tracing baryon assembly via cold gas, dust, and metals, and identifying quenching pathways and timescales—along with the instrumental capabilities needed (dust continuum, FIR fine-structure lines, and broad spectral coverage). The proposed facility would bridge JWST-era discoveries with FIR diagnostics, enabling a coherent picture of early baryon cycles, feedback, and the environmental context of massive halos, with wide practical impact on models of early structure formation.
Abstract
The first few billion years of cosmic history witnessed the rapid emergence of the most massive galaxies, yet their true space density, baryon assembly pathways, and early quenching mechanisms remain poorly constrained. Current surveys lack the wide-field, rest-frame FIR sensitivity needed to obtain a complete census of massive systems and to trace their cold gas, dust, and diffuse emission on galactic and circumgalactic scales. A next-generation facility with a very large aperture, wide field of view, and high mapping speed is essential to carry out deep, degree-scale rest-frame FIR surveys. Such capabilities are required to determine how common massive galaxies are, how they assemble their baryons, and what physical processes drive their early transformation and quenching.