Observational discrimination among high-redshift galaxy-growth mechanisms

Determine which physical mechanism among feedback-free bursts, gas-surface-density-regulated star formation, violent-disk-instability starbursts, and dark-matter-accelerated star formation is favored by observations of high-redshift galaxy abundances and luminosity functions.

Background

The paper compares several proposed explanations for the unexpectedly high abundance of massive galaxies at cosmic dawn. SAGE26 uses feedback-free bursts, while other studies invoke gas surface-density-dependent star-formation efficiencies, starbursts from violent disk instabilities, or dark-matter-driven accelerated star formation.

Because multiple mechanisms reproduce the currently available observables, the authors state that present constraints cannot distinguish among them. Improved observations and additional theoretical predictions are therefore needed to identify which mechanism is physically responsible for the rapid growth of massive galaxies at very high redshift.

References

The fact that several different mechanisms can reproduce the same observables indicates the present constraints do not yet discriminate between them, and further routes are likely to be proposed as the data improves.

— SAGE26 Paper I: Modelling the baryon cycle from cosmic dawn to the present day  (2610.09564 - Bradley et al., 7 Oct 2026) in Section 8, “Feedback-Free Bursts”