We study the imprint of light scalar fields on gravitational waves from extreme mass ratio inspirals -- binary systems with a very large mass asymmetry. We first show that, to leading order in the mass ratio, any effects of the scalar on the waveform are captured fully by two parameters: the mass of the scalar and the scalar charge of the secondary compact object. We then use this theory-agnostic framework to show that the future observations by LISA will be able to simultaneously measure both of these parameters with enough accuracy to detect ultra-light scalars.
@article{arxiv.2212.03888,
title = {Detecting massive scalar fields with Extreme Mass-Ratio Inspirals},
author = {Susanna Barsanti and Andrea Maselli and Thomas P. Sotiriou and Leonardo Gualtieri},
journal= {arXiv preprint arXiv:2212.03888},
year = {2023}
}