Stellar Signatures of Inhomogeneous Big Bang Nucleosynthesis

We evaluate abundance anomalies generated in patches of the Universe where the baryon-to-photon ratio was locally enhanced by possibly many orders of magnitude in the range η=10-10–10-1. Our study is motivated by the possible survival of rare dense regions in the early Universe, the most extreme of which, above a critical threshold, collapsed to form primordial black holes. If this occurred, one may expect there to also be a significant population of early-forming stars that formed in similar but subthreshold patches. We derive a range of element abundance signatures by performing BBN simulations at high values of the baryon-to-photon ratio that may be detectable in any surviving first-generation stars of around a solar mass. Our predictions apply to metal-poor Galactic halo stars, to old globular star clusters, and to dwarf galaxies, and we compare with observations in each of these cases.