Tidal Effects for Black Holes with Scalar Hair in EsGB Gravity

Abstract

After the groundbreaking detection of Gravitational Waves in 2015, a new era looms of unprecedented new data of the strong field gravity regime. The need for well-developed theories beyond General Relativity is therefore high. Einstein-scalar-Gauss-Bonnet gravity is one of the most promising quadratic gravity theories, and has recently had its Lagrangian calculated to 1PN order. In this thesis, we include the tidal effects induced on the scalar field around the black hole in the action and derive its contribution to the 1PN Lagrangian. A small mistake in the Lagrangian is also corrected. Finally, we calculate the binding energy and relative acceleration from the Lagrangian, and we specifically analyse the magnitude of the tidal contribution to the binding energy. The contribution is found to be generally small in most situations, but also to be heavily dependent on yet unknown parameters. The relative magnitude of the tidal contribution is found to be up to 10^-5 compared to the GR energy in some situations.