Testing Gravitational-Wave Signal From Verification Binaries with Space-Based Gravitational-Wave Detectors

TL;DR

This study assesses the detection prospects and parameter estimation accuracy of space-based gravitational wave detectors for known ultra-compact binaries, highlighting the advantages of detector networks in multi-messenger astronomy.

Contribution

It provides a comprehensive evaluation of 73 verification binaries' detectability and parameter estimation with current and future space-based GW detector networks.

Findings

DECIGO detects 71 sources at SNR ≥ 5, more than other detectors.

Detector networks significantly improve detection numbers and parameter precision.

Enhanced networks enable better multi-messenger astronomy and understanding of UCBs.

Abstract

Space-based gravitational wave (GW) detectors will open the millihertz band to survey ultra-compact binaries (UCBs). \textit{Verification binaries} (VBs) is a key to verifying the performance of space-based GW detectors because its parameters are known from electromagnetic observations and it is expected to be a detectable source of GW. We evaluated 73 VBs, computing their detection prospects and parameter estimation precision for individual GW detectors and networks. Among single detectors, DECIGO shows the highest sensitivity, detecting 71 sources at signal-to-noise ratio $\rho$ $\geq$ 5, compared to 42 for LISA, 32 for Taiji, and 27 for TianQin, while the full TianQin + LISA + Taiji + DECIGO network improves this to 73 detectable sources. For parameter estimation, individual detectors achieve median precisions on the order of $\sim 10^{-2}-10^{-1} \, \text{M}_{\odot}$ for chirp mass, $\sim 1\,\text{kpc}$ for distance, $\sim 1-17\,\text{deg}$ for inclination and $\sim 10^{-4}-10^{-2}\,\text{deg}^2$ for sky localization. The complete TianQin + LISA + Taiji + DECIGO network enhances these constraints substantially, reducing the median uncertainties to approximately $\sim 10^{-2} \, \text{M}_{\odot}$ in chirp mass, $\sim 10^{-2}\,\text{kpc}$ in distance, $\sim 1\,\text{deg}$ in inclination and $\sim 10^{-4}\,\text{deg}^2$ in sky localization. The upcoming space-based GW detectors, especially their networks, have outstanding observational capabilities for UCB, which will advance our research on multi-messenger astronomy and deepen our understanding of UCB in the Milky Way.