Extreme mass-ratio inspirals as probes of scalar fields: inclined circular orbits around Kerr black holes

Abstract

Extreme mass-ratio inspirals, a target source for the space-based gravitational wave detector LISA, are a sensitive probe of fundamental scalar fields coupled to gravity. We assess the capability of LISA to detect whether the secondary compact object is endowed with a scalar field, in the case of inclined orbits. We show that the imprint of the scalar field depends on the orbital inclination, and is significantly larger for prograde orbits.