RH 1.5D: a massively parallel code for multi-level radiative transfer with partial frequency redistribution and Zeeman polarisation

Abstract

The emergence of three-dimensional magneto-hydrodynamic (MHD) simulations of stellar atmospheres has sparked a need for efficient radiative transfer codes to calculate detailed synthetic spectra. We present RH 1.5D, a massively parallel code based on the RH code and capable of performing Zeeman polarised multi-level non-local thermodynamical equilibrium (NLTE) calculations with partial frequency redistribution for an arbitrary amount of chemical species. The code calculates spectra from 3D, 2D or 1D atmospheric models on a column-by-column basis (or 1.5D). While the 1.5D approximation breaks down in the cores of very strong lines in an inhomogeneous environment, it is nevertheless suitable for a large range of scenarios and allows for faster convergence with finer control over the iteration of each simulation column. The code scales well to at least tens of thousands of CPU cores, and is publicly available. In the present work we briefly describe its inner workings, strategies for convergence optimisation, its parallelism, and some possible applications.

6 pages, 3 figures. A&A in press. Updated version reflects changes in latest proofs

References in corpus (6)

• 3D Hydrodynamical Simulations of Surface Convection in Red Giant Stars. Impact on spectral line formation and abundance analysis
• Magnetic flux emergence in granular convection: Radiative MHD simulations and observational signatures
• Twisted flux tube emergence from the convection zone to the corona
• Improvements to Stellar Structure Models, Based on a Grid of 3D Convection Simulations. I. $T(\tau )$-Relations
• Energy transport, overshoot, and mixing in the atmospheres of M-type main- and pre-main-sequence objects
• Sulphur abundances from the SI near-infrared triplet at 1045 nm

Cited by in corpus (14)

• On the generation of solar spicules and Alfvénic waves
• Intermittent reconnection and plasmoids in UV bursts in the low solar atmosphere
• Ellerman bombs and UV bursts: transient events in chromospheric current sheets
• 3D NLTE analysis of the most iron-deficient star, SMSS0313-6708
• Modeling Mg II h, k and Triplet Lines at Solar Flare Ribbons
• Solar Ellerman Bombs in 1-D Radiative Hydrodynamics
• RADYN simulations of non-thermal and thermal models of Ellerman bombs
• Semi-empirical model atmospheres for the chromosphere of the sunspot penumbra and umbral flashes
• Modelling of Mg II lines in solar prominences
• The Response of the Lyman-Alpha Line in Different Flare Heating Models
• The Formation of IRIS Diagnostics. IX. The Formation of the C I 135.58 Line in the Solar Atmosphere
• Spatio-temporal evolution of Hanle and Zeeman synthetic polarization in a chromospheric spectral line
• Opacity distribution functions for stellar spectra synthesis
• The key role of solar dynamics in the chromospheric Hanle polarization