Dark-Matter-Free Star Formation at Cosmic Dawn: Physical Plausibility and Observational Signatures of a Transient Baryonic Channel

The existence of dark-matter-deficient galaxies such as NGC 1052-DF2 and DF4 establishes that stellar systems can form and persist without a dominant dark matter halo — not as a theoretical possibility, but as an empirical fact. This raises a concrete question: if such formation is physically possible, could it have been common in the early Universe, where baryon densities were orders of magnitude higher and dark matter halos had not yet virialized? We explore this question by examining high-velocity collisions between primordial gas clouds at z > 10, driven by differential spins in the pre-virialized IGM. Rather than assuming specific parameters, we ask the inverse question: what are the minimum physical conditions under which baryonic collapse without DM support becomes possible? We show that these threshold conditions are consistent with the early Universe environment. The collision rate scales as (1 + z)6, making this a transient phenomenon that closes by z ∼ 6 through cosmic dilution. Critically, the scarcity of DM-free galaxies today does not constrain the historical frequency of this channel: most products would have been dominated by massive, short-lived stars and, lacking a DM halo to provide gravitational confinement, would have dispersed after feedback — leaving behind chemical enrichment of the IGM, orphaned globular clusters, and intragroup stellar streams rather than bound galaxies. DF2 and DF4 are the rare survivors of a potentially ubiquitous process. We map all expected fates of this channel and identify the corresponding observational signatures accessible to JWST, ALMA, Euclid, and ELT, framing this as an invitation to a systematic observational search.