Spin Diagrams for Equal-Mass Black-Hole Binaries with Aligned Spins

TL;DR

This paper presents spin diagrams for equal-mass black-hole binaries with aligned spins, providing a straightforward way to estimate recoil velocities and final spins from initial parameters, based on extensive simulations.

Contribution

The authors constructed spin diagrams for equal-mass, aligned-spin black-hole binaries, offering new tools to predict recoil velocities and final spins from initial conditions.

Findings

Maximum recoil velocity of 441.94 km/s

Final spin range from 0.3471 to 0.9591

Spin diagrams accurately predict merger outcomes

Abstract

Binary black-hole systems with spins aligned with the orbital angular momentum are of special interest as they may be the preferred end-state of the inspiral of generic supermassive binary black-hole systems. In view of this, we have computed the inspiral and merger of a large set of binary systems of equal-mass black holes with spins aligned with the orbital angular momentum but otherwise arbitrary. By least-square fitting the results of these simulations we have constructed two "spin diagrams" which provide straightforward information about the recoil velocity |v_kick| and the final black-hole spin a_fin in terms of the dimensionless spins a_1 and a_2 of the two initial black holes. Overall they suggest a maximum recoil velocity of |v_kick|=441.94 km/s, and minimum and maximum final spins a_fin=0.3471 and a_fin=0.9591, respectively.