The Lightweaver Framework for NLTE Radiative Transfer in Python

TL;DR

The Lightweaver framework offers a flexible, modular Python toolkit for NLTE radiative transfer simulations, combining ease of use with high computational speed, thus enabling rapid exploration of complex spectral line modeling.

Contribution

It introduces a new Python-based toolkit that balances flexibility and speed for NLTE radiative transfer, improving accessibility and customization in the field.

Findings

Achieves high speed comparable to existing tools

Provides a flexible, modular architecture for complex simulations

Demonstrates applicability through user-interactive components

Abstract

Tools for computing detailed optically thick spectral line profiles out of local thermodynamic equilibrium have always been focused on speed, due to the large computational effort involved. With the Lightweaver framework, we have produced a more flexible, modular toolkit for building custom tools in a high-level language, Python, without sacrificing speed against the current state of the art. The goal of providing a more flexible method for constructing these complex simulations is to decrease the barrier to entry and allow more rapid exploration of the field. In this paper we present an overview of the theory of optically thick NLTE radiative transfer, the numerical methods implemented in Lightweaver including the problems of time-dependent populations and charge-conservation, as well as an overview of the components most users will interact with, to demonstrate their flexibility.