Stochastic background of relic scalar gravitational waves from scalar-tensor gravity

TL;DR

This paper explores the generation and characteristics of a scalar component of relic gravitational waves within scalar-tensor gravity, analyzing its spectrum and constraints from cosmological data.

Contribution

It introduces the primordial production of scalar gravitational waves in scalar-tensor gravity and assesses their potential detectability considering WMAP constraints.

Findings

Scalar modes of gravitational waves are produced alongside tensor modes.

The spectrum of relic scalar gravitational waves is distinctive and potentially observable.

Upper limits on scalar wave amplitude are derived from WMAP data.

Abstract

A stochastic background of relic gravitational waves is achieved by the so called adiabatically-amplified zero-point fluctuations process derived from early inflation. In principle, it provides a distinctive spectrum of relic gravitational waves. In the framework of scalar-tensor gravity, we discuss the scalar modes of gravitational waves and the primordial production of this scalar component which is generated beside tensorial one. We discuss also the upper limit for such a relic scalar component with respect to the WMAP constraints.