Lyα Radiative Transfer: Modeling Spectrum and Surface Brightness Profiles of Lyα-emitting Galaxies at Z = 3–6

Abstract

Abstract We perform Lyα radiative transfer calculations to reproduce the Lyα properties of star-forming galaxies at high redshifts. We model a galaxy as a halo in which the density distributions of Lyα 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 the Multi-Unit Spectroscopic Explorer using this outflowing-halo model with Lyα scattering. The best-fit model parameters (i.e., the outflowing velocity and optical depth) for these galaxies are consistent with those in other studies. We examine the impacts of individual model parameters and input spectrum on the emerging spectrum and surface brightness profile. Further investigations of the correlations among observables (i.e., the spatial extent of Lyα halos and Lyα spectral features) and model parameters, and of 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 on the spatial/kinematic distributions of the medium.