Geodesic properties in terms of multipole moments in scalar-tensor theories of gravity

TL;DR

This paper develops a formalism linking multipole moments of scalar-tensor gravity objects to observable geodesic properties, aiding the understanding of deviations from general relativity.

Contribution

It provides explicit expressions for geodesic observables in scalar-tensor theories using multipole moments, enhancing analysis of scalarized compact objects.

Findings

Expressions for geodesic observables in terms of multipole moments.

Insights into how scalarization affects gravitational observables.

Framework to detect deviations from general relativity.

Abstract

The formalism for describing a metric and the corresponding scalar in terms of multipole moments has recently been developed for scalar-tensor theories. We take advantage of this formalism in order to obtain expressions for the observables that characterise geodesics in terms of the moments. These expressions provide some insight into how the structure of a scalarized compact object affects observables. They can also be used to understand how deviations from general relativity are imprinted on the observables.