Detecting massive scalar fields with Extreme Mass-Ratio Inspirals

TL;DR

This paper demonstrates that future LISA gravitational wave observations can detect ultra-light scalar fields by analyzing their effects on extreme mass-ratio inspirals, using a simplified two-parameter model.

Contribution

It introduces a model-independent framework showing how scalar field effects can be characterized by two parameters, enabling detection prospects with upcoming gravitational wave data.

Findings

LISA can measure scalar mass and charge accurately

Scalar effects are captured by two key parameters

Future observations can detect ultra-light scalars

Abstract

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.