Detection strategies for scalar gravitational waves with interferometers and resonant spheres

TL;DR

This paper analyzes detection strategies for scalar gravitational waves using interferometers and resonant spheres, focusing on response functions, optimal configurations, and correlations, especially in the context of Brans-Dicke theory.

Contribution

It introduces a method to optimize the correlation between interferometers and resonant spheres for scalar GWs detection, including specific frequency and distance considerations.

Findings

Maximum correlation at finite f*d for interferometer-sphere pairs

Optimal resonance frequency for Virgo and a nearby sphere is 590 Hz

Discussion on challenges of applying analysis to string theory scalar fields

Abstract

We compute the response and the angular pattern function of an interferometer for a scalar component of gravitational radiation in Brans-Dicke theory. We examine the problem of detecting a stochastic background of scalar GWs and compute the scalar overlap reduction function in the correlation between an interferometer and the monopole mode of a resonant sphere. While the correlation between two interferometers is maximized taking them as close as possible, the interferometer-sphere correlation is maximized at a finite value of f*d, where `f' is the resonance frequency of the sphere and `d' the distance between the detectors. This defines an optimal resonance frequency of the sphere as a function of the distance. For the correlation between the Virgo interferometer located near Pisa and a sphere located in Frascati, near Rome, we find an optimal resonance frequency f=590 Hz. We also briefly discuss the difficulties in applying this analysis to the dilaton and moduli fields predicted by string theory.