Ab uno disce omnes: Single-harmonic search for extreme mass-ratio inspirals

TL;DR

This paper introduces a fast, semi-coherent time-frequency search method for detecting extreme mass-ratio inspirals (EMRIs) in gravitational wave data, achieving high detection probability and parameter estimation accuracy without full waveform templates.

Contribution

It develops a novel, efficient detection pipeline based on phenomenological frequency evolution modeling, suitable for large-scale EMRI searches in LISA data.

Findings

94% detection probability at SNR=30

1% relative error in dominant harmonic frequency recovery

Sub-percent precision in intrinsic parameter estimation

Abstract

Extreme mass-ratio inspirals (EMRIs) are one of the key sources of gravitational waves for space-based detectors such as LISA. However, their detection remains a major data analysis challenge due to the signals' complexity and length. We present a semi-coherent, time-frequency search strategy for detecting EMRI harmonics without relying on full waveform templates. We perform an injection and search campaign of single mildly-eccentric equatorial EMRIs in stationary Gaussian noise. The detection statistic is constructed solely from the EMRI frequency evolution, which is modeled phenomenologically using a Singular Value Decomposition basis. The pipeline and the detection statistic are implemented in time-frequency, enabling efficient searches over one year of data in approximately one hour on a single GPU. The search pipeline achieves 94% detection probability at $\mathrm{SNR} = 30$ for a false-alarm probability of $10^{-2}$, recovering the frequency evolution of the dominant harmonic to 1% relative error. By mapping the EMRI parameters consistent with the recovered frequency evolution, we show that the semi-coherent detection statistic enables a sub-percent precision estimation of the EMRI intrinsic parameters. These results establish a computationally efficient framework for constructing EMRI proposals for the LISA global fit.