Quasi-equilibrium initial data in alternative theories of Gravity

Numerical relativity simulations in alternative theories of gravity are necessary to investigate the strong field, dynamical behavior of such theories. Any such simulation starts from initial data which should be mathematically consistent (i.e. satisfy the constraint equations) while maintaining desired physical properties. This talk reports on recent progress in constructing initial data for single and binary black holes within Einstein-Scalar-Gauss-Bonnet gravity. The requirement that the black holes are in quasi-equilibrium results in elliptic problems which are singular at the BH horizons. We demonstrate successful numerical solutions using the SpECTRE code.