3D Heat Transport, Burning, and Evolution

CI:- Dr. A. Heger

Understanding and modeling heat transport mechanisms in different mediums is a fundamental concept of astrophysics. It has applications from nuclear burning in stars, to asymmetric heat patches on the surface of stars and compact objects in binary systems, to heating on planets, engineering applications. We have developed a multi-dimensional time-dependent implicit model of heating, ignition, and burning with different geometries, equations of states, and compositions. Initially, we developed the code to model Type I X-ray bursts on the surface of accreting neutron stars, the most frequently observed thermonuclear explosions in the universe. The general nature as a multi-D heat transport code, however, allows a much wider range of applications both in the astrophysical community, such as Type Ia supernovae, binary stars, as well as planetary sciences. We request assistance packaging and publishing the code on PyPI so it may be used by the wider community. Understanding thermonuclear explosions and the systems that produce them gives us insight into fundamental physics such as the dense equation of state, nuclear reactions we cannot replicate on Earth, and the influence of strong magnetic and gravitational fields. X-ray bursts have been comprehensively modeled in 1D since the 1970s, but multi-D models have not been feasible due to computational limitations; our code is changing this. From the successful ADACs 2021A proposal we now have a fast-solving MPI version of the heat code but still require assistance for parallelising our framework of detailed nuclear reaction calculations that contribute to heating. The nuclear reaction network is embarrassingly parallel across the grid, but requires weaving in with the parallel heat solver. We thus request assistance in parallelising the nuclear reaction networks into the MPI framework, such that we may be able to run the first detailed 3D model of an X-ray burst.