University Events

Description: "Quasi-equilibrium initial data in modified theories of gravity" - Abstract: In order to perform theory-specific tests of black hole mergers observed by LIGO, we need accurate predictions of their behavior in alternative theories of gravity. Recent efforts to numerically simulate compact objects in alternative theories of gravity have largely focused on the time-evolution equations. Another critical aspect is the construction of constraint-satisfying initial data with precise control over the properties of the systems under consideration. In this talk, I will discuss recent efforts to extend techniques to construct stationary initial data for black hole systems in GR to scalar-tensor theories of gravity and their numerical implementation in the open-source SpECTRE code. Despite the resulting elliptic system being singular at black hole horizons, we demonstrate how to construct numerical solutions that extend smoothly across the horizon. We obtain quasistationary scalar hair configurations in the test-field limit for black holes with linear/angular momentum as well as for black hole binaries. For isolated black holes, we explicitly show that the scalar profile obtained is stationary by evolving the system in time and compare against previous formulations of scalar Gauss-Bonnet initial data. In the case of the binary, we find that the scalar hair near the black holes can be markedly altered by the presence of the other black hole. The initial data constructed here enables targeted simulations in scalar Gauss-Bonnet simulations with reduced initial transients. Contact: zchen2@umassd.edu