Limits to the Primordial Helium Abundance in the Baryoninhomogeneous Big Bang
Abstract
The parameter space for baryon inhomogeneous big bang models is explored with the goal of determining the minimum helium abundance obtainable in such models while still satisfying the other lightelement constraints. We find that the constraint of (D + He3)/H less than 10 exp 4 restricts the primordial helium mass fraction from baryoninhomogeneous big bang models to be greater than 0.231 even for a scenario which optimizes the effects of the inhomogeneities and destroys the excess lithium production. Thus, this modification to the standard big bang as well as the standard homogeneous big bang model itself would be falsifiable by observation if the primordial He4 abundance were observed to be less than 0.231. Furthermore, a present upper limit to the observed helium mass fraction of Y(obs)(p) less than 0.24 implies that the maximum baryontophoton ratio allowable in the inhomogeneous models corresponds to eta less than 2.3 x 10 exp 9 (omega(b) hsquared less than 0.088) even if all conditions are optimized.
 Publication:

The Astrophysical Journal
 Pub Date:
 February 1993
 DOI:
 10.1086/172302
 Bibcode:
 1993ApJ...404..476M
 Keywords:

 Baryons;
 Big Bang Cosmology;
 Cosmochemistry;
 Helium;
 Astronomical Models;
 Nuclear Fusion;
 Astrophysics;
 COSMOLOGY: EARLY UNIVERSE;
 ELEMENTARY PARTICLES;
 NUCLEAR REACTIONS;
 NUCLEOSYNTHESIS;
 ABUNDANCES