Dominique Aubert
Univ. Strasbourg (Strasbourg, France)
This perspective triggered a number of developments to accompany the expected flow of new data. For a few years, we have been developing in Strasbourg new cosmological simulation tools to study the Reionization process. These tools participate to the strong ongoing effort by the community to include the radiative transfer physics in numerical simulations. Given its central role in the transition, one might want to deal routinely with light in the same way as we deal with matter in such codes. However, the inclusion of light is known to be quite challenging in terms of numerical ressources and can increase by orders of magnitude the complexity or the numerical requirements of the existing codes. I will present how we were led to use graphics processing units (GPUs) as hardware accelerators to cope with this numerical challenge and I will discuss the methodologies of ATON, a radiative post-processing code and EMMA, a new complete AMR cosmological simulation code, both accelerated by means of graphics devices.
This codes have been already used to model the large scale reionization, in particular to investigate the dependance of the global physical properties of the reionizing Universe (ionization state, UV flux or ionization fronts geometry) on the source models. These tools have also been applied to simulations of the Local Group to study the impact of the reionization on the properties of the Milky Way, M31 and their satellite populations, notably via the production of a massive simulation that ran on 8000 GPUs. I will discuss these first results and how they provide some insights on the interplay between matter and radiation, especially on the star formation in young galaxies. However, numerical models of reionization are still at their initial stages and I will also discuss the difficulties encountered during our first investigations and how they pave the way to future projects.
Amphithéâtre Henri Mineur, Institut d'Astrophysique de Paris