AlterBBN: A program for calculating the BBN abundances of the elements in alternative cosmologies

TL;DR

AlterBBN is a public C program that calculates primordial element abundances from Big-Bang nucleosynthesis, allowing modifications of cosmological parameters to test various models against BBN constraints.

Contribution

It introduces a versatile tool that enables the simulation of BBN under different cosmological assumptions, facilitating testing of alternative cosmological models.

Findings

Allows modification of baryon-to-photon ratio, neutrino number, expansion rate, and entropy during BBN.

Enables confrontation of cosmological models with BBN observational constraints.

Provides a comprehensive manual explaining the physics and features of the program.

Abstract

We describe AlterBBN, a public C program for evaluating the abundances of the elements generated by Big-Bang nucleosynthesis (BBN). This program enables the user to compute the abundances of the elements in the standard model of cosmology, and additionally provides possibilities to alter the assumptions of the cosmological model in order to study their consequences on the abundances of the elements. In particular the baryon-to-photon ratio and the effective number of neutrinos, as well as the expansion rate and the entropy content of the Universe during BBN can be modified in AlterBBN. Such features allow the user to test the cosmological models by confronting them to BBN constraints. A presentation of the physics of BBN and the features of AlterBBN is provided here under the form of a manual.