ROGALLO · Fluid dynamics of binary systems composed of stars and black holes

This project aims to conduct previously unachievable (magneto)hydrodynamical simulations of binary systems involving stars, planets, neutron stars, and black holes. The phenomena occurring in these systems lie at the heart of some of the most important unsolved astrophysical problems, such as the evolutionary origin of gravitational wave sources, the acceleration sites of high-energy particles, and the coevolution of galaxies with their supermassive black holes. Advancements in the theoretical understanding of these phenomena are urgently needed to interpret observations from a wide range of current and future ground- and space-based facilities. Traditionally, numerical simulations of fluid dynamics in binary systems have relied on general-purpose codes that either discretize matter into particles or divide space into finite volume elements organized in an unstructured or logically-Cartesian mesh, such as spherical or cylindrical coordinates. However, these approaches lose accuracy or yield unphysical results when applied to the complicated, yet largely predictable, structure of binary systems. To achieve a dramatically higher level of realism in fluid dynamics simulations of binary systems, I will develop a new 3D parallel multiphysics code, ROGALLO. This code will be based on the discontinuous Galerkin method coupled with complex meshes specifically adapted to structures arising in binary systems. Leveraging the most recent developments in numerical mathematics, I will use ROGALLO to substantially advance the theory of fundamental processes such as pulsations, turbulence, mixing, mass transfer and mass loss, accretion, and explosions for a wide variety of binary systems. These systems include tidally-deformed or mass-transferring stars, chemically-homogeneous gravitational wave progenitors, classical novae, Type Ia supernovae, circumbinary disks around supermassive black holes, or gaseous bodies moving through fluid.