Scalar Mode Quadrupole Radiation from Astronomical Sources in $F(R)$ Modified Gravity

TL;DR

This paper analyzes scalar mode quadrupole radiation in $F(R)$ gravity, deriving explicit formulas and exploring potential detectability in gravitational wave observations from astronomical sources.

Contribution

It provides explicit expressions for scalar quadrupole radiation in $F(R)$ gravity and examines its detectability from astrophysical sources.

Findings

Scalar mode radiates even under spherical symmetry.

Explicit formulas for scalar quadrupole radiation derived.

Potential for future detection of scalar modes in gravitational waves.

Abstract

We investigate the scalar mode quadrupole radiation of gravitational waves in $F(R)$ modified gravity. In $F(R)$ gravity a massive scalar mode appears in the gravitational waves. We find explicit expressions for the quadrupole radiation and the energy current of the scalar mode in general $F(R)$ gravity models. We consider a binary star and a bouncing star as astronomical sources of the gravitational waves and calculate the quadrupole radiation of the scalar and tensor modes. The scalar mode radiates under spherically symmetric conditions, but the tensor modes do not. The scalar mode mass is estimated for some typical energy scales. We show a possibility to detect the scalar mode in the future gravitational waves observation.