1.5D NLTE spectral synthesis of a 3D filament/prominence simulation

TL;DR

This paper demonstrates the application of the Lightweaver framework for non-LTE spectral synthesis on a 3D MHD filament/prominence simulation, enabling detailed spectral analysis of solar structures with good agreement to observations.

Contribution

It extends Lightweaver to 1.5D spectral synthesis on 3D MHD filament models, including new boundary conditions and line formation analysis for multiple spectral lines.

Findings

Excellent agreement between 1.5D Lightweaver synthesis and Hα proxy.

Computed additional spectral lines like Ca II 8542 and Mg II h&k.

Validated filament/prominence models against observational line contrast.

Abstract

Aims. We here demonstrate how the recently developed Lightweaver framework makes non-LTE (NLTE) spectral synthesis feasible on a new 3D ab-initio magnetohydrodynamic (MHD) filament/prominence simulation, in a post-processing step. Methods. We clarify the need to introduce filament/prominent-specific Lightweaver boundary conditions that accurately model incident chromospheric radiation, and include a self-consistent and smoothly varying limb darkening function. Results. Progressing from isothermal/isobaric models to the self-consistently generated stratifications within a fully 3D MHD filament/prominence simulation, we find excellent agreement between our 1.5D non local thermodynamic equilibrium Lightweaver synthesis and a popular Hydrogen H{\alpha} proxy. We compute additional lines including Ca~\textsc{ii} 8542 alongside the more optically-thick Ca~\textsc{ii} H&K & Mg~\textsc{ii} h&k lines, for which no comparable proxy exists, and explore their formation properties within filament/prominence atmospheres. Conclusions. The versatility of the Lightweaver framework is demonstrated with this extension to 1.5D filament/prominence models, where each vertical column of the instantaneous 3D MHD state is spectrally analysed separately, without accounting for (important) multi-dimensional radiative effects. The general agreement found in the line core contrast of both observations and the Lightweaver-synthesised simulation further validates the current generation of solar filaments/prominences models constructed numerically with MPI-AMRVAC.