Relativistic Fluid Simulations in Nonlinear Gravity

Current models of cosmology predict the formation of black holes near the beginning of the Universe’s life that are not a result of stellar collapse. These black holes, called Primordial Black Holes (PBH), could help explain our currently incomplete understanding of the origin of intermediate massive black holes and the composition of dark matter. Exactly how PBH are formed, however, has not been studied rigorously. We investigate the possible formation of PBH from primordial density fluctuations. We model the radiation present in the Universe at the time as a relativistic fluid which interacted with gravity, treated fully non-linearly. To do this, we employ a Grid And Bubble Evolver in General Relativity, GABERel, which evolves scalar fields within the BSSN formalism. I will present the progress we have made toward employing this formalism and studying the evolution of these primordial density perturbations.