A radiative transfer scheme for cosmological reionization based on a local Eddington tensor

A radiative transfer scheme is presented, based on a moment description of the equation of radiative transfer and the so–called “M1 closure model” for the Eddington tensor. This model features a strictly hyperbolic transport step for radiation : it has been implemented using standard Godunov–like techniques in a new code called ATON. Coupled to simple models of ionization chemistry and photo-heating, ATON is able to reproduce the results of other schemes on a various set of standard tests such as the expansion of a HII region, the shielding of the radiation by dense clumps and cosmological ionization by multiple sources. Being simple yet robust, such a scheme is intended to be naturally and easily included in grid–based cosmological fluid solvers.