Strong Interactions in the Three Black Holes Problem

Abstract

We study the three-body problem from different perspectives, going from classical Newtonian physics to general relativity. In the classical case, we modeled the interactions in a typical chaotic configuration, identifying strong interaction times (SITs), namely transients in which the system manifests complex, highly energetic dynamics. By selecting one of such SITs as an initial condition for the general relativistic case, we perform simulations of numerical relativity, showing net differences with the Newtonian case. In the relativistic case, comparing also with the more "quiet" two-body inspiral, we observed strong nonlinear emission of gravitational waves. The spectrum of the three-body signals during a SIT might be a guidance for future gravitational waves observations.

On the stability of covariant BSSN formulation

“…The Baumgarte-Shapiro-Shibata-Nakamura (BSSN) formulation [8][9][10], Z4 formulation [11][12][13][14], generalized harmonic formulation [15][16][17] are well known to improve numerical stability. The spectral or pseudo-spectral methods [18][19][20][21][22][23] are also widely used in numerical relativists. There are also several comprehensive books in numerical relativity (e.g.…”