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In this paper we present CRASH_alpha, the first radiative transfer code for cosmological application that follows the parallel propagation of Ly_alpha and ionizing photons. CRASH_alpha is a version of the continuum radiative transfer code CRASH with a new algorithm to follow the propagation of Ly_alpha photons through a gas configuration whose ionization structure is evolving. The implementation introduces the time evolution for Ly_alpha photons (a feature commonly neglected in line radiative transfer codes) and, to reduce the computational time needed to follow each scattering, adopts a statistical approach to the Ly_alpha treatment by making extensive use of pre-compiled tables. With this statistical approach we experience a drastic increase of the computational speed and, at the same time, an excellent agreement with the full Ly_alpha radiative transfer computations of the code MCLy_alpha. We find that the emerging spectra keep memory of the ionization history which generates a given ionization configuration of the gas and, to properly account for this effect, a self-consistent joint evolution of line and ionizing continuum radiation as implemented in CRASH_alpha is necessary. A comparison between the results from our code and from Ly_alpha scattering alone on a fixed HI density field shows that the extent of the difference between the emerging spectra depends on the particular configuration considered, but it can be substantial and can thus affect the physical interpretation of the problem at hand. These differences should furthermore be taken into account when computing the impact of the Ly_alpha radiation on e.g. the observability of the 21 cm line from neutral hydrogen at epochs preceeding complete reionization.
Thermal dust emission carries information on physical conditions and dust properties in many astronomical sources. Because observations represent a sum of emission along the line of sight, their interpretation often requires radiative transfer modell
Radiative transfer modelling is part of many astrophysical simulations and is used to make synthetic observations and to assist analysis of observations. We concentrate on the modelling of the radio lines emitted by the interstellar medium. In connec
Context. Magnetic fields are important to the dynamics of many astrophysical processes and can typically be studied through polarization observations. Polarimetric interferometry capabilities of modern (sub)millimeter telescope facilities have made i
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
Aims. We present MCFOST-art, a new non-local thermodynamic equilibrium radiative transfer solver for multilevel atomic systems. The code is embedded in the 3D radiative transfer code MCFOST and is compatible with most of the MCFOST modules. The code