Lyman-alpha radiative transfer: Modeling spectrum and surface brightness profile of Lyman-alpha emitting galaxies at z=3-6

TL;DR

This study models Lyman-alpha radiative transfer in high-redshift star-forming galaxies, successfully reproducing observed spectra and surface brightness profiles to better understand galaxy outflows and medium properties.

Contribution

It introduces a halo model with outflows and dust to accurately simulate Lyman-alpha emission, matching observations and constraining galaxy medium characteristics.

Findings

Reproduced spectra and surface brightness profiles of galaxies at z=3-6.

Best-fit model parameters align with previous studies.

Combined spectral and brightness data tightly constrain galaxy medium properties.

Abstract

We perform Lyman-alpha radiative transfer calculations for reproducing Lyman-alpha properties of star-forming galaxies at high redshifts. We model a galaxy as a halo in which the density distributions of Lyman-alpha sources and H I plus dust medium are described with exponential functions. We also consider an outflow of the medium that represents a momentum-driven wind in a gravitational potential well. We successfully reproduce both the spectra and the surface brightness profiles of eight star-forming galaxies at z =3-6 observed with MUSE using this outflowing halo model with Lyman-alpha scattering. The best-fit model parameters (i.e., the outflowing velocity and optical depth) for these galaxies are consistent with other studies. We examine the impacts of individual model parameters and input spectrum on emerging spectrum and surface brightness profile. Further investigations on correlations among observables (i.e., the spatial extent of Lyman-alpha halos and Lyman-alpha spectral features) and model parameters, and spatially resolved spectra are presented as well. We demonstrate that the combination of spectrum and surface brightness profile provides strong constraints on model parameters and thus spatial/kinematic distributions of medium.