Stellar Signatures of Inhomogeneous Big Bang Nucleosynthesis

TL;DR

This paper investigates how early universe regions with high baryon-to-photon ratios could lead to unique element abundance signatures in ancient stars, providing insights into primordial inhomogeneities and black hole formation.

Contribution

It introduces a method to predict element abundance signatures from inhomogeneous Big Bang nucleosynthesis at high baryon-to-photon ratios, linking to observable ancient stars.

Findings

Predicted element signatures in metal-poor stars and globular clusters.

Potential detection of inhomogeneous BBN effects in old stellar populations.

Constraints on early universe density fluctuations from stellar observations.

Abstract

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 $\eta = 10^{-10} - 10^{-1}$. 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.