# Dipolar tidal effects in scalar-tensor theories

## TL;DR

This paper investigates how scalar-tensor theories modify tidal effects in gravitational waves, introducing new scalar tidal Love numbers and assessing their detectability with future space-based detectors.

## Contribution

It introduces a new class of scalar-type tidal Love numbers and computes their effects on gravitational wave signals in scalar-tensor theories.

## Key findings

- Scalar tidal Love numbers depend on a time-varying scalar dipole.
- Tidal effects could be detectable by LISA or third-generation detectors.
- First computation of tidal contributions in wave generation for scalar-tensor theories.

## Abstract

The inclusion of finite-size effects in the gravitational waveform templates allows not only to constrain the internal structure of compact objects, but to test deviations from general relativity. Here, we address the problem of tidal effects in massless scalar-tensor theories. We introduce a new class of scalar-type tidal Love numbers due to the presence of a time-varying scalar dipole moment. We compute the leading-order tidal contribution in the conservative dynamics and for the first time in the wave generation for quasi-circular orbits. Importantly, we show that in a system dominated by dipolar emission, such tidal effects may be detectable by LISA or third generation detectors.