# LIGO Seminar

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Speaker: Mekhi Dhesi

**Modeling Black Hole Binaries in the Intermediate-Mass-Ratio Regime**

Intermediate-mass-ratio inspirals (IMRIs) remain an important open problem in gravitational-wave source modelling. While black hole perturbation theory can accurately model extreme-mass-ratio inspirals, and numerical relativity has seen much success modelling comparable-mass inspirals, neither approach works well on its own for IMRIs. It is not clear how adequate a purely perturbative treatment can be at intermediate mass ratios of 1:100-1:1000, and the length-scale disparity remains large enough to pose a serious challenge for numerical relativity.

We are working to provide accurate modelling of such binaries through a synergistic combination of black-hole perturbation and numerical relativity techniques. Our approach matches an approximate analytical solution (formed from the tidally perturbed metric of the smaller black hole) to a fully nonlinear numerical solution in the bulk of the spacetime. We will first explain this architecture using a simple toy model of a scalar charge in orbit around a Schwarzschild black hole, and present results from a numerical implementation of such a test setup in 1+1D, as well as preliminary results in 3+1D. We will then discuss the application of our approach to the binary black-hole problem itself.

Zoom link: https://caltech.zoom.us/j/82072539167