Black hole simulations in bi-scalar gravity

The search for modifications to Einstein's theory of general relativity has become increasingly intriguing as recent and upcoming gravitational wave experiments open a new window to probe gravity with compact objects such as black holes. One natural extension to general relativity arises from considering the addition of stringy corrections in the low-energy approximation which introduces a coupled scalar field. In this talk, I will take this a step further and consider scalar-tensor theories of gravity which introduce two scalar fields coupled to curvature as well as each other, as such interactions are not ruled out by solar system tests. To consider the effect of these interactions in strong gravity environments, I will present numerical simulations of two scalar fields evolving around a black hole to consider the formation of scalar profiles around the black hole, known as scalar hair, as well as potential instabilities.