Spin effects on the dynamics of compact binaries

TL;DR

This paper discusses how spin influences the evolution of compact binary systems, which are key sources for gravitational wave detection, and explores the theoretical modeling of spinning bodies including neutron star properties.

Contribution

It introduces a gauge symmetry related to the spin supplementary condition and discusses universal relations between neutron star multipole moments.

Findings

Spin effects significantly impact binary evolution.

Universal relations simplify neutron star modeling.

Gauge symmetry arises from spin supplementary conditions.

Abstract

Compact binaries are the most promising source for the advanced gravitational wave detectors, which will start operating this year. The influence of spin on the binary evolution is an important consequence of general relativity and can be large. It is argued that the spin supplementary condition, which is related to the observer dependence of the center, gives rise to a gauge symmetry in the action principle of spinning point-particles. These spinning point-particles serve as an analytic model for extended bodies. The internal structure can be modelled by augmenting the point-particle with higher-order multipole moments. Consequences of the recently discovered universal (equation of state independent) relations between the multipole moments of neutron stars are discussed.