LINX: A Fast, Differentiable, and Extensible Big Bang Nucleosynthesis Package

TL;DR

LINX is a new, fast, and differentiable Big Bang Nucleosynthesis code that enables efficient Bayesian inference and joint analysis with CMB data, accessible even on personal hardware.

Contribution

LINX introduces a differentiable BBN code using JAX, allowing rapid parameter estimation and joint CMB-BBN analysis without heavy computational demands.

Findings

Achieves fast primordial abundance predictions

Enables gradient-based Bayesian inference

Facilitates joint CMB and BBN analysis on personal hardware

Abstract

We introduce LINX (Light Isotope Nucleosynthesis with JAX), a new differentiable public Big Bang Nucleosynthesis (BBN) code designed for fast parameter estimation. By leveraging JAX, LINX achieves both speed and differentiability, enabling the use of Bayesian inference, including gradient-based methods. We discuss the formalism used in LINX for rapid primordial elemental abundance predictions and give examples of how LINX can be used. When combined with differentiable Cosmic Microwave Background (CMB) power spectrum emulators, LINX can be used for joint CMB and BBN analyses without requiring extensive computational resources, including on personal hardware.