Effects of the variation of fundamental constants on Pop III stellar evolution

TL;DR

This study investigates how variations in fundamental constants influence Population III stellar evolution, deriving limits on these variations based on nucleosynthesis outcomes in early stars.

Contribution

It introduces a microscopic model linking fundamental constant variations to stellar nucleosynthesis, providing new constraints from Population III star evolution.

Findings

Limits of permille level on nuclear interaction variation

Order 10^{-5} limits on fine structure constant variation

Constraints applicable to cosmological redshift z ~ 15-20

Abstract

A variation of the fundamental constants is expected to affect the thermonuclear rates important for stellar nucleosynthesis. In particular, because of the very small resonant energies of Be8 and C12, the triple $\alpha$ process is extremely sensitive to any such variations. Using a microscopic model for these nuclei, we derive the sensitivity of the Hoyle state to the nucleon-nucleon potential allowing for a change in the magnitude of the nuclear interaction. We follow the evolution of 15 and 60 solar mass, zero metallicity stellar models, up to the end of core helium burning. These stars are assumed to be representative of the first, Population III stars. We derive limits on the variation of the magnitude of the nuclear interaction and model dependent limits on the variation of the fine structure constant based on the calculated oxygen and carbon abundances resulting from helium burning. The requirement that some C12 and O16 be present are the end of the helium burning phase allows for permille limits on the change of the nuclear interaction and limits of order 10^{-5} on the fine structure constant relevant at a cosmological redshift of z ~ 15-20.