Probing time-dependent scalar wigs with extreme mass ratio inspirals

TL;DR

This paper explores how a time-dependent scalar field around black holes influences gravitational waves from extreme mass ratio inspirals, finding minimal impact on waveforms and orbital dynamics.

Contribution

It develops a new formalism to compute scalar perturbations in EMRIs with scalar wigs and analyzes their effect on gravitational wave emission.

Findings

Scalar field has negligible effect on orbital motion.

Scalar wig induces additional fluxes in gravitational waves.

Waveforms remain largely unaffected by the scalar field.

Abstract

We investigate the gravitational wave emission from extreme mass ratio inspirals, key targets for the upcoming space-based detector LISA, considering the scenario where the lighter black hole in the binary is endowed by a long-lived, time-dependent scalar field configuration, known as a scalar wig. We develop a formalism to compute scalar perturbations for extreme mass ratio inspirals on circular orbits around Schwarzschild and Kerr black holes, and apply this framework to compute additional fluxes induced by the scalar wig as well as their dependence on the scalar field properties. Our computation provides strong indications that in this scenario the presence of the scalar field does not significantly affect the orbital motion and the gravitational waveform.