Amplification of the primordial gravitational waves energy spectrum by a kinetic scalar in F(R) gravity
Abstract
In this work we consider a combined theoretical framework comprised by F(R) gravity and a kinetic scalar field. The kinetic energy of the scalar field dominates over its potential for all cosmic times, and the kinetic scalar potential is chosen to be small and nontrivial. In this case, we show that the primordial gravitational wave energy spectrum of vacuum F(R) gravity is significantly enhanced and can be detectable in future interferometers. The kinetic scalar thus affects significantly the inflationary era, since it extends its duration, but also has an overall amplifying effect on the energy spectrum of pure F(R) gravity primordial gravitational waves. The form of the signal is characteristic for all these theories, since it is basically flat and should be detectable from all future gravitational wave experiments for a wide range of frequencies, unless some unknown damping factor occurs due to some unknown physical process.
 Publication:

Astroparticle Physics
 Pub Date:
 January 2023
 DOI:
 10.1016/j.astropartphys.2022.102777
 arXiv:
 arXiv:2209.09781
 Bibcode:
 2023APh...14402777O
 Keywords:

 Primordial gravitational waves;
 Kinetic scalar;
 Inflation;
 Reheating era;
 General Relativity and Quantum Cosmology;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 High Energy Physics  Theory
 EPrint:
 Astroparticle Physics in press