Tiny galaxies vanish from the early universe, study suggests

A JWST-backed study using gravitational lensing of galaxy cluster Abell 2744 analyzes faint, distant galaxies from the Epoch of Reionization. It finds a drop-off in ultrafaint galaxies—faint-end suppression—contradicting the expectation that there should be many more tiny galaxies. The result implies early radiation heated surrounding gas, preventing star formation in low‑mass halos and challenging the idea that the smallest galaxies powered reionization; however, conclusions depend on the cluster's lens model, and more JWST data across additional clusters are needed to confirm whether this is a universal trend.