DeSIRe: Departure coefficient aided Stokes Inversion based on Response functions

Abstract

Future ground-based telescopes, such as the 4-metre class facilities DKIST and EST, will dramatically improve on current capabilities for simultaneous multi-line polarimetric observations in a wide range of wavelength bands, from the near-ultraviolet to the near-infrared. As a result, there will be an increasing demand for fast diagnostic tools, i.e., inversion codes, that can infer the physical properties of the solar atmosphere from the vast amount of data these observatories will produce. The advent of substantially larger apertures, with the concomitant increase in polarimetric sensitivity, will drive an increased interest in observing chromospheric spectral lines. Accordingly, pertinent inversion codes will need to take account of line formation under general non-local thermodynamic equilibrium (NLTE) conditions. Several currently available codes can already accomplish this, but they have a common practical limitation that impairs the speed at which they can invert polarised spectra, namely that they employ numerical evaluation of the so-called response functions to changes in the atmospheric parameters, which makes them less suitable for the analysis of very large data volumes. Here we present DeSIRe (Departure coefficient aided Stokes Inversion based on Response functions), an inversion code that integrates the well-known inversion code SIR with the NLTE radiative transfer solver RH. The DeSIRe runtime benefits from employing analytical response functions computed in local thermodynamic equilibrium (through SIR), modified with fixed departure coefficients to incorporate NLTE effects in chromospheric spectral lines. This publication describes the operating fundamentals of DeSIRe and describes its behaviour, robustness, stability, and speed. The code is ready to be used by the solar community and is being made publicly available.

arXiv comment15 pages, 9 figures, regular paper

References in corpus (21)

• The chemical composition of the Sun
• The stellar atmosphere simulation code Bifrost
• Sunrise: instrument, mission, data and first results
• The Sunrise Mission
• A publicly available simulation of an enhanced network region of the Sun
• An Open Source, Massively Parallel Code for Non-LTE Synthesis and Inversion of Spectral Lines and Zeeman-induced Stokes Profiles
• STiC -- A multi-atom non-LTE PRD inversion code for full-Stokes solar observations
• Inversion of the radiative transfer equation for polarized light
• Bombs and flares at the surface and lower atmosphere of the Sun
• Non-LTE inversions of the Mg II h&k and UV triplet lines
• Ellerman bombs and UV bursts: transient events in chromospheric current sheets
• Non-local thermodynamic equilibrium inversions from a 3D MHD chromospheric model
• Radiative diagnostics in the solar photosphere and chromosphere
• Spectropolarimetric capabilities of Ca II 8542 A line
• Spectropolarimetric NLTE inversion code SNAPI
• Heating of the magnetic chromosphere: observational constraints from Ca II 8542 spectra
• Chromospheric polarimetry through multi-line observations of the 850 nm spectral region
• Preliminary design of the Visible Spectro-Polarimeter for the Advanced Technology Solar Telescope
• Machine learning initialization to accelerate Stokes profile inversions
• Design and Performance Analysis of a Highly Efficient Polychromatic Full-Stokes Polarization Modulator for the CRISP Imaging Spectrometer
• Solar polarimetry in the K I $D_2$ line: A novel possibility for a stratospheric balloon

Cited by in corpus (24)

• The European Solar Telescope
• Waves in the lower solar atmosphere: the dawn of next-generation solar telescopes
• TIC: A Stokes inversion code for scattering polarization with partial frequency redistribution and arbitrary magnetic fields
• Spatio-temporal analysis of chromospheric heating in a plage region
• IBIS-A: The IBIS data Archive. High resolution observations of the solar photosphere and chromosphere with contextual data
• $IRI{S}^{2+}$: A comprehensive database of stratified thermodynamic models in the low solar atmosphere
• Evaluating Non-LTE Spectral Inversions with ALMA and IBIS
• Spectropolarimetric Inversion in Four Dimensions with Deep Learning (SPIn4D): I. Overview, Magnetohydrodynamic Modeling, and Stokes Profile Synthesis
• Ambipolar Diffusion in the Lower Solar Atmosphere: MHD Simulations of a Sunspot
• Chromospheric velocities in an M3.2 flare using He I 1083.0 nm and Ca II 854.2 nm
• A study of the capabilities for inferring atmospheric information from high-spatial-resolution simulations
• Impact of opacity effects on chromospheric oscillations inferred from NLTE inversions
• Understanding the thermal and magnetic properties of a X-class flare in the low solar atmosphere
• Magnetic diffusion in Solar atmosphere produces measurable electric fields
• Does H$\alpha$ Stokes~$V$ profiles probe the chromospheric magnetic field? An observational perspective
• Diagnosing the solar atmosphere through the Mg I b${}_2$ 5173 Å line. II. Morphological classification of the intensity and circular polarization profiles
• Recovering thermodynamics from spectral profiles observed by IRIS (II): improved calculation of the uncertainties based on Monte Carlo experiments
• Simultaneous spectropolarimetric observations in the H$\alpha$ and Ca II 8662 Å lines of an active region
• Neural translation for Stokes inversion and synthesis
• Exploring magnetic loops and serpentine fields in the quiet Sun with the GRIS-IFU
• Non-Local Thermodynamic Equilibrium inversions of the Si I 10827 A spectral line
• Derivation of Instrument Requirements for Polarimetry using Mg, Fe, and Mn lines between 250 and 290 nm
• An iterative OLA method for inversion of solar spectropolarimetric data: I. Single and multiple variable inversions of thermodynamic quantities
• Accelerating 3D Non-LTE Synthesis with Graph Neural Networks