2025MNRAS.536L...8R

Early JWST observations have revealed the ubiquitous presence in the early Universe, up to $z\sim \! 16$, of extreme baryon concentrations, namely forming globular clusters, extremely dense galaxies that may or may not be UV bright, and supermassive black holes in relatively low-mass galaxies. This paper is trying to pinpoint which physical conditions may have favoured the formation of such concentrations, that appear to be very common at high redshifts while their formation being progressively more and more rare at lower redshifts. Building on local globular cluster evidence, it is argued that such conditions can consist in a combination of a ${\sim} \! 10$ Myr extended feedback free time, coupled to low angular-momentum densities in deep local minima of the ISM vorticity field, where baryon concentrations are more likely to form. It is argued that the former condition would follow from more massive stars failing to explode as supernovae, and the latter one from low vorticity prevailing in the early Universe, in contrast to later times with their secular increase of the angular momentum density due to the cumulative effect of tidal interactions.