RSAA Colloquium: Dr Hayley MacPherson from University of Melbourne

Numerical relativity as a tool for precision cosmology

High-precision cosmological surveys are expected to deliver measurements at sub-percent precision. In order to ensure we correctly interpret these data, we need to be sure that our theoretical model is accurate. Within general relativity, the standard cosmological model adopts many approximations for gravitational interactions and geometry. These approximations have served us well so far, but as our error bars grow smaller and smaller we need to know at exactly what point they fail. Numerical relativity is a computational method which allows us to relax simplifying assumptions for gravity and geometry and consider the full interaction of matter and space-time as described by general relativity. 
 

I will provide some background on the use of numerical relativity for cosmological simulations before discussing the generation of synthetic observables in these simulations which are also free from common simplifying assumptions. This from-first-principles framework is exciting in its potential to quantify exactly when our approximations fail and might begin to bias our cosmological constraints.