Parameter-estimation bias induced by transient orbital resonances in extreme-mass-ratio inspirals

TL;DR

Transient orbital resonances in EMRIs significantly affect gravitational wave signals, causing biases in parameter estimation and potential detection issues if not properly modeled.

Contribution

This study quantifies the bias caused by transient resonances in EMRI parameter estimation using a Fisher-matrix approach, emphasizing the importance of accurate resonance modeling.

Findings

Neglecting resonance effects leads to significant SNR loss.

Resonance-induced modifications impact parameter recovery.

Accurate modeling of resonance effects is crucial for EMRI science.

Abstract

Given the multi-frequency nature of relativistic orbits, transient orbital resonances are expected to be ubiquitous during an extreme-mass-ratio inspiral (EMRI). At a resonance, the orbital dynamics is modified in a nontrivial way, imprinting an overall dephasing in the emitted gravitational waves and potentially impacting both the detection and parameter estimation of these sources. In this work, using a Fisher-matrix approach, we investigate the bias induced by transient orbital resonances in EMRI parameter estimation. We focus on the most dynamically significant low-order resonances, 3 : 2 and 2 : 1, as well as on the high-order, subdominant resonances 3 : 1 and 4 : 3. We find that, for most of the orbits considered, neglecting the effect of a resonance crossing leads to significant losses in signal-to-noise ratio and induces bias in parameter recovery. Furthermore, both the sign and the amplitude of the resonance-induced modifications to the integrals of motion play a crucial role and must be modeled accurately. Our results provide further evidence that failing to model transient orbital resonances accurately can hinder EMRI detection and parameter estimation, thereby limiting their scientific potential.