SEURAT: SPH scheme extended with ultraviolet line radiative transfer

TL;DR

SEURAT is a new Monte Carlo radiative transfer code that adaptively models Lyman alpha photon propagation in complex, inhomogeneous systems like star-forming galaxies, improving the accuracy of spectral predictions.

Contribution

The paper introduces SEURAT, a novel SPH-based Lyman alpha radiative transfer code with adaptive scattering resolution and dust absorption, capable of handling complex inhomogeneous environments.

Findings

Successfully verified with standard test cases

Accurately models Lyα spectra in complex systems

Handles highly inhomogeneous density fields

Abstract

We present a novel Lyman alpha (Ly$\alpha$) radiative transfer code, SEURAT, where line scatterings are solved adaptively with the resolution of the smoothed particle hydrodynamics (SPH). The radiative transfer method implemented in SEURAT is based on a Monte Carlo algorithm in which the scattering and absorption by dust are also incorporated. We perform standard test calculations to verify the validity of the code; (i) emergent spectra from a static uniform sphere, (ii) emergent spectra from an expanding uniform sphere, and (iii) escape fraction from a dusty slab. Thereby we demonstrate that our code solves the Ly$\alpha$ radiative transfer with sufficient accuracy. We emphasise that SEURAT can treat the transfer of Ly$\alpha$ photons even in highly complex systems that have significantly inhomogeneous density fields. The high adaptivity of SEURAT is desirable to solve the propagation of Ly$\alpha$ photons in the interstellar medium of young star-forming galaxies like Ly$\alpha$ emitters (LAEs). Thus, SEURAT provides a powerful tool to model the emergent spectra of Ly$\alpha$ emission, which can be compared to the observations of LAEs.