Stellar Oscillations in Scalar-Tensor Theory of Gravity

TL;DR

This paper investigates how scalar-tensor theories of gravity affect relativistic star oscillations, revealing that scalar fields cause measurable shifts in gravitational wave frequencies, which could serve as indirect evidence for such theories.

Contribution

It derives perturbation equations for relativistic stars in scalar-tensor gravity and demonstrates how scalar fields influence gravitational wave spectra.

Findings

Frequency shifts are proportional to scalar field strength.

Scalar waves may be produced but are likely undetectable due to low energy.

Spectral shifts can indicate scalar fields without direct scalar wave detection.

Abstract

We derive the perturbation equations for relativistic stars in scalar-tensor theories of gravity and study the corresponding oscillation spectrum. We show that the frequency of the emitted gravitational waves is shifted proportionally to the scalar field strength. Scalar waves which might be produced from such oscillations can be a unique probe for the theory, but their detectability is questionable if the radiated energy is small. However we show that there is no need for a direct observation of scalar waves: the shift in the gravitational wave spectrum could unambiguously signal the presence of a scalar field.