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Main Authors: Chan, Tsang Keung, Richings, Alexander J., Theuns, Tom, Liu, Yuankang, Schaller, Matthieu, Ivkovic, Mladen
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2508.13277
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author Chan, Tsang Keung
Richings, Alexander J.
Theuns, Tom
Liu, Yuankang
Schaller, Matthieu
Ivkovic, Mladen
author_facet Chan, Tsang Keung
Richings, Alexander J.
Theuns, Tom
Liu, Yuankang
Schaller, Matthieu
Ivkovic, Mladen
contents We present SPARCS, which combines the moment-based radiative transfer method SPH-M1RT with the non-equilibrium metal chemistry solver CHIMES in the modern highly-parallel astrophysical code SWIFT. SPARCS enables on-the-fly radiation hydrodynamics simulations, with multi-frequency ultraviolet radiative transfer coupled with all ionisation states of 11 major elements, in the presence of dust, cosmic ray ionization and heating, and self-gravity. Direct radiation pressure on gas and dust is also accounted for. We validate SPARCS against analytic solutions and standard photo-ionization codes such as CLOUDY in idealized tests. As an example application, we simulate an ionization front propagating through an inhomogeneous interstellar medium with solar metallicity. We produce mock optical emission line observations with the level population calculation code HyLight and the diagnostic radiative transfer code RADMC3D. We find that non-equilibrium effects and inhomogeneities can boost the low ion fractions by up to an order of magnitude. Possible applications of SPARCS include studying the dynamical impact of radiation on gas in star-forming regions, and in the interstellar and circumgalactic medium, as well as interpreting line diagnostics in such environments, and galactic or AGN outflows.
format Preprint
id arxiv_https___arxiv_org_abs_2508_13277
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SPARCS -- combining radiation hydrodynamics with non-equilibrium metal chemistry in the SWIFT astrophysical code
Chan, Tsang Keung
Richings, Alexander J.
Theuns, Tom
Liu, Yuankang
Schaller, Matthieu
Ivkovic, Mladen
Astrophysics of Galaxies
Instrumentation and Methods for Astrophysics
We present SPARCS, which combines the moment-based radiative transfer method SPH-M1RT with the non-equilibrium metal chemistry solver CHIMES in the modern highly-parallel astrophysical code SWIFT. SPARCS enables on-the-fly radiation hydrodynamics simulations, with multi-frequency ultraviolet radiative transfer coupled with all ionisation states of 11 major elements, in the presence of dust, cosmic ray ionization and heating, and self-gravity. Direct radiation pressure on gas and dust is also accounted for. We validate SPARCS against analytic solutions and standard photo-ionization codes such as CLOUDY in idealized tests. As an example application, we simulate an ionization front propagating through an inhomogeneous interstellar medium with solar metallicity. We produce mock optical emission line observations with the level population calculation code HyLight and the diagnostic radiative transfer code RADMC3D. We find that non-equilibrium effects and inhomogeneities can boost the low ion fractions by up to an order of magnitude. Possible applications of SPARCS include studying the dynamical impact of radiation on gas in star-forming regions, and in the interstellar and circumgalactic medium, as well as interpreting line diagnostics in such environments, and galactic or AGN outflows.
title SPARCS -- combining radiation hydrodynamics with non-equilibrium metal chemistry in the SWIFT astrophysical code
topic Astrophysics of Galaxies
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2508.13277