Abstract. We present early results from a study addressing the question of how one treats the propagation of incertitude, that is, epistemic uncertainty, in input parameters in astrophysical simulations. As an example, we look at the propagation of incertitude in control parameters for stellar winds in MESA stellar evolution simulations. We apply two methods of incertitude propagation, the Cauchy Deviates method and the Quadratic Response Surface method, to quantify the output uncertainty in the final white dwarf mass given a range of values for wind parameters. The methodology we apply is applicable to the problem of propagating input incertitudes through any simulation code treated as a "black box," i.e. a code for which the algorithmic details are either inaccessible or prohibitively complicated. We have made the tools developed for this study freely available to the community.
IntroductionMuch of theoretical astrophysics relies on large-scale simulation for progress because phenomena of interest typically incorporate multiple physical processes interacting over a wide range of scales. Even study of the basic processes, e.g. plasma and fluid dynamics, requires simulations that can challenge extant computer architectures. Because of both the importance of simulation and the dynamic nature of state-of-the-art computer architectures, considerable resources go into the development and maintenance of simulation codes. Many of these advanced codes, built with person-years of development effort, are made publicly available and are used currently by many investigators in addition to the original developers.Despite the capabilities of modern codes and architectures, uncertainty imposes limits on the results of simulations. This issue is often neglected in studies in part because of the difficulty in addressing it. As with verification and validation, uncertainty quantification is critical to credible computational science, particularly in astrophysics where most simulation results are predictions, that is, a description of the state of a system under conditions for which the computational model has not been validated [1,2,3].