An Open Source, Massively Parallel Code for Non-LTE Synthesis and Inversion of Spectral Lines and Zeeman-induced Stokes Profiles

TL;DR

NICOLE is an open-source, massively parallel code designed for non-LTE spectral line synthesis and inversion, enabling detailed analysis of solar chromospheric spectro-polarimetric data from large datasets.

Contribution

This paper introduces NICOLE, a new open-source, parallelized code for non-LTE radiative transfer, specifically tailored for spectral synthesis and inversion of solar spectro-polarimetric observations.

Findings

Enables analysis of large solar datasets with high computational efficiency

Supports spectral synthesis and inversion across multiple atmospheric heights

Facilitates detailed interpretation of chromospheric spectro-polarimetry

Abstract

With the advent of a new generation of solar telescopes and instrumentation, the interpretation of chromospheric observations (in particular, spectro-polarimetry) requires new, suitable diagnostic tools. This paper describes a new code, NICOLE, that has been designed for Stokes non-LTE radiative transfer, both for synthesis and inversion of spectral lines and Zeeman-induced polarization profiles, spanning a wide range of atmospheric heights, from the photosphere to the chromosphere. The code fosters a number of unique features and capabilities and has been built from scratch with a powerful parallelization scheme that makes it suitable for application on massive datasets using large supercomputers. The source code is being publicly released, with the idea of facilitating future branching by other groups to augment its capabilities.