Can we Detect Intermediate Mass Ratio Inspirals?

TL;DR

This paper investigates the challenges in detecting intermediate-mass-ratio inspirals (IMRIs) via gravitational waves, focusing on waveform modeling issues due to the breakdown of approximations at critical orbital phases.

Contribution

It analyzes the limitations of current waveform models for IMRIs and discusses the importance of including spin effects for improved detection accuracy.

Findings

Waveform mismatches increase as the system approaches the innermost stable circular orbit.

Current perturbative solutions are insufficient for accurate IMRI waveform modeling.

Including spin of the smaller body could be crucial for detection.

Abstract

Gravitational waves emitted during intermediate-mass-ratio inspirals (IMRIs) of intermediate-mass black holes (IMBHs) into supermassive black holes could represent a very interesting source for LISA. Similarly, IMRIs of stellar-mass compact objects into IMBHs could be detectable by Advanced LIGO. At present, however, it is not clear what waveforms could be used for IMRI detection, since the post-Newtonian approximation breaks down as an IMRI approaches the innermost stable circular orbit, and perturbative solutions are only known to the lowest order in the mass ratio. We discuss the expected mismatches between approximate and true waveforms, and the choice of the best available waveform as a function of the mass ratio and the total mass of the system. We also comment on the significance of the spin of the smaller body and the need for its inclusion in the waveforms.