Dipolar tidal effects in 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.