Surprises from the spins: astrophysics and relativity with detections of spinning black-hole mergers

TL;DR

This paper explores how black-hole spins, measured through gravitational waves, reveal insights into their astrophysical origins and relativistic phenomena, uncovering surprising behaviors and constraints.

Contribution

It provides new examples demonstrating the interplay between spin dynamics in relativity and astrophysical environmental effects in black-hole mergers.

Findings

Black-hole spins show unexpected morphologies and resonances.

Spins constrain supernova kick velocities.

Multiple merger generations influence spin configurations.

Abstract

Measurements of black-hole spins are of crucial importance to fulfill the promise of gravitational-wave astronomy. On the astrophysics side, spins are perhaps the cleanest indicator of black-hole evolutionary processes, thus providing a preferred way to discriminate how LIGO's black holes form. On the relativity side, spins are responsible for peculiar dynamical phenomena (from precessional modulations in the long inspiral to gravitational-wave recoils at merger) which encode precious information on the underlying astrophysical processes. I present some examples to explore this deep and fascinating interplay between spin dynamics (relativity) and environmental effects (astrophysics). Black-hole spins indeed hide remarkable surprises on both fronts: morphologies, resonances, constraints on supernova kicks, multiple merger generations and more...