Evaluating statistical significance for massive black hole binary mergers with space-based gravitational wave detectors

TL;DR

This paper develops a framework to evaluate the statistical significance of massive black hole binary detections with space-based gravitational wave detectors, ensuring reliable scientific discoveries in future observations.

Contribution

It introduces a novel method to assess detection significance and mitigate confusion noise, applied to simulated and complex datasets for space-based gravitational wave signals.

Findings

MBHBs with SNR ~7 reach 3σ significance

MBHBs with SNR ~8 reach 4σ significance

All signals in LDC-2a dataset exceed 4.62σ significance

Abstract

Important scientific discoveries should be backed by high statistical significance. In the 2030s, multiple space-based gravitational wave detectors are expected to operate. While many works aim to achieve quick and reliable detection and parameter estimation of millihertz gravitational wave sources, dedicated studies are lacking to assess the significance of space-based detectors. In this work, we propose a framework to assess the statistical significance of massive black hole binaries (MBHBs) detections with space-based gravitational wave detectors. We apply this algorithm to simulated data with Gaussian stationary noise and the complex LDC-2a dataset to measure the false alarm rate and significance of MBHB signals. We also analyze factors affecting the significance of MBHBs and design a method to mitigate multi-source confusion interference. In Gaussian noise conditions, MBHBs with a signal-to-noise ratio of about 7 can achieve $3 \sigma$ significance, and those with a signal-to-noise ratio of about 8 achieve $4 \sigma$. Our analysis demonstrates that all MBHB signals in the LDC-2a dataset have a significance exceeding $4.62 \sigma$.