Perturbative solution of the Einstein Constraints with Spin and Momentum Far Away From a Binary Source in the Bowen-York formalism

TL;DR

This paper presents an analytical perturbative solution to the Einstein constraints for two black holes with spins and momenta in the Bowen-York formalism, valid at large separations, aiding numerical relativity.

Contribution

It provides the first perturbative analytical solution for the Einstein constraints with spinning black holes at large distances in the Bowen-York formalism.

Findings

Derived an analytical solution for black holes with spins and momenta

Computed the apparent horizon's shape and location depending on parameters

The solution is valid for large separations from the black holes

Abstract

We study the momentum and Hamiltonian constraints of vacuum Einstein equations, within the Bowen-York formalism, for two interacting black holes in close separation, with anti-parallel spins and anti-parallel linear momenta. We give an analytical solution using perturbation theory. We also compute the location and the shape of the apparent horizon which generically depend on all the parameters, angles and the separation between the black holes. Our solution only works for distances far away from the black holes. To gain more insight close to the black holes, one has to go to the higher orders in perturbation theory, which is a rather cumbersome process. But the solution presented here can be of some use for numerical computations as the latter should match our result for the described problem.