Open Question on the Physical Origins of Massive Early-Universe Systems

Determine the physical origins of massive systems observed in the early Universe—including UV-bright galaxies at redshift z ≳ 9, broad-line massive active galactic nuclei at z ≈ 8.5, dusty massive starbursts at z ≈ 6.9, and overdensities of massive dusty galaxies at z ≈ 4.3—by isolating the roles of star-formation efficiency, feedback, and dark matter assembly.

Background

The report notes that recent JWST and ALMA observations have revealed numerous massive systems at high redshift whose properties are difficult to reconcile with current galaxy formation models. This motivates a focused investigation into their physical origins and the interplay of star-formation efficiency, feedback processes, and dark matter assembly.

Resolving this open question is central to understanding early galaxy ecosystems and informs the facilities and observational strategies needed, including ngVLA, enhanced ALMA sensitivity or large single-dish mm/submm telescopes, and wide-field FIR imaging spectroscopy.