Conservative Spin-Magnitude Change in Orbital Evolution in General Relativity

Area of Science:

• * Gravitational physics and astrophysics.
• * Relativistic celestial mechanics.
• * Compact object dynamics.

Background:

• * Current models of compact spinning objects in general relativity primarily use spin vectors.
• * Physical observables like impulse and waveforms are assumed to depend solely on these spin vectors.
• * A deeper understanding of spin tensor effects is crucial for precise gravitational wave predictions.

Purpose of the Study:

• * To investigate if physical scattering observables depend on degrees of freedom beyond the spin vector.
• * To explore the implications of these additional degrees of freedom for compact objects.
• * To connect these effects to the eikonal phase.

Main Methods:

• * Analysis of physical scattering observables in general relativity for compact spinning objects.
• * Examination of conservative Hamiltonian evolution.
• * Relating impulse, spin kick, and waveform dependence to the spin tensor structure.
• * Utilizing the eikonal phase as a probe.

Main Results:

• * Scattering observables depend on additional degrees of freedom in the spin tensor, not just the spin vector.
• * The magnitude of the spin vector changes during conservative Hamiltonian evolution, indicating this extra structure.
• * These additional degrees of freedom correspond to dynamical mass multipoles, which are absent in black holes.
• * The conservative impulse, spin kick, and evolution of these extra degrees of freedom are encoded in the eikonal phase.

Conclusions:

• * Compact spinning objects possess richer spin dynamics than previously modeled.
• * The spin tensor's full structure influences gravitational interactions and waveforms.
• * These findings necessitate refined models for analyzing gravitational wave data from compact object mergers.