Probing the Tidal Deformability of the Central Object in an Extreme Mass Ratio Inspiral with Analytic Kludge Waveforms

Abstract: We develop approximate ``analytic-kludge" waveforms to describe the inspiral of a stellar-mass compact object into a supermassive compact object in an extreme mass ratio inspiral (EMRI) scenario. The deformability of the supermassive compact object is characterized by a dimensionless quantity called the tidal Love number (TLN). Our analysis shows that, up to the leading order of the mass ratio, the conservative dynamics of the EMRI are not affected by tidal interaction, and the tidal effect is only present in the induced quadrupole moment. We calculate the energy and angular momentum fluxes and obtain leading order corrections to the orbital evolution equations. By comparing the waveforms with and without tidal interaction, we demonstrate that even a small TLN can produce significant differences in the waveforms, which can be detected by space-borne detector LISA. Finally, using the Fisher information matrix method, we perform parameter estimation for the TLN and find that the precision can reach the level of $10<sup>{-4}$ in suitable scenarios.