No abstract

We study the post-Newtonian dynamics of black hole binaries in Einstein-scalar-Gauss-Bonnet gravity theories. To this aim we build static, spherically symmetric black hole solutions at fourth order in the Gauss-Bonnet coupling α. We then "skeletonize" these solutions by reducing them to point particles with scalar field-dependent masses, showing that this procedure amounts to fixing the Wald entropy of the black holes during their slow inspiral. The cosmological value of the scalar field plays a crucial role in the dynamics of the binary. We compute the two-body Lagrangian at first post-Newtonian order and show that no regularization procedure is needed to obtain the Gauss-Bonnet contributions to the fields, which are finite. We illustrate the power of our approach by Padé-resumming the so-called "sensitivities," which measure the coupling of the skeletonized body to the scalar field, for some specific theories of interest. arXiv:1909.05258v1 [gr-qc]

Starting from the static, spherically symmetric black hole solutions in massless Einstein-Maxwelldilaton (EMD) theories, we build a "skeleton" action, that is, we phenomenologically replace black holes by an appropriate effective point particle action, which is well suited to the formal treatment of the many-body problem in EMD theories. We find that, depending crucially on the value of their scalar cosmological environment, black holes can undergo steep "scalarization" transitions, inducing large deviations to the general relativistic two-body dynamics, as shown, for example, when computing the first post-Keplerian Lagrangian of EMD theories.1 Note that a = 0 reduces to Einstein-Maxwell theory minimally coupled to a scalar field, while a = 0 is motivated by low-energy limits of string theory, see, e.g., [18]; a = √ 3 is equivalent to the dimensional reduction of the Kaluza-Klein theory [19] [20].