DIAPHANE: A portable radiation transport library for astrophysical applications

One of the most computationally demanding aspects of the hydrodynamical modelingof Astrophysical phenomena is the transport of energy by radiation or relativistic particles. Physical processes involving energy transport are ubiquitous and of capital importance in many scenarios ranging from planet formation to cosmic structure evolution, including explosive events like core collapse supernova or gamma-ray bursts. Moreover, the ability to model and hence understand these processes has often been limited by the approximations and incompleteness in the treatment of radiation and relativistic particles. The diaphane project has focused on developing a portable and scalable library that handles the transport of radiation and particles (in particular neutrinos) independently of the underlying hydrodynamic code. In this work, we present the computational framework and the functionalities of the first version of the diaphane library, which has been successfully ported to three different smoothed-particle hydrodynamic codes, gadget2, gasoline and sphynx. We also present validation of different modules solving the equations of radiation and neutrino transport using different numerical schemes.