On Detecting Stellar Binary Black Holes via the LISA-Taiji Network

TL;DR

This paper assesses the potential of the LISA-Taiji space-based gravitational wave network to detect stellar binary black holes, estimating detection rates, parameter estimation accuracy, and the benefits of combined observations over extended periods.

Contribution

It provides a detailed analysis of sBBH detection prospects with the LISA-Taiji network, including rate estimates and parameter uncertainties, based on simulated populations constrained by LIGO/Virgo data.

Findings

LISA-Taiji could detect dozens to over a hundred sBBHs in 4 to 10 years.

Detection rates are 2-3 times higher with the network than with LISA or Taiji alone.

Parameter estimation uncertainties are within 5-20% for luminosity distance and 1-100 deg² for sky localization.

Abstract

The detection of gravitational waves (GWs) by ground-based laser interferometer GW observatories (LIGO/Virgo) reveals a population of stellar binary black holes (sBBHs) with (total) masses up to $\sim 150M_\odot$, which are potential sources for space-based GW detectors, such as LISA and Taiji. In this paper, we investigate in details on the possibility of detecting sBBHs by the LISA-Taiji network in future. We adopt the sBBH merger rate density constrained by LIGO/VIRGO observations to randomly generate mock sBBHs samples. Assuming an observation period of $4$ years, we find that the LISA-Taiji network may detect several tens (or at least several) sBBHs with signal-to-noise ratio (SNR) $>8$ (or $>15$), a factor $2-3$ times larger than that by only using LISA or Taiji observations. Among these sBBHs, no more than a few that can merge during the $4$-year observation period. If extending the observation period to $10$ years, then the LISA-Taiji network may detect about one hundred (or twenty) sBBHs with SNR $>8$ (or $>15$), among them about twenty (or at least several) can merge within the observation period. Our results suggest that the LISA-Taiji network may be able to detect at least a handful to twenty or more sBBHs even if assuming a conservative SNR threshold ($15$) for ``detection'', which enables multi-band GW observations by space and ground-based GW detectors. We also further estimate the uncertainties in the parameter estimations of the sBBH systems ``detected'' by the LISA-Taiji network. We find that the relative errors in the luminosity distance measurements and sky localization are mostly in the range of $0.05-0.2$ and $1-100\deg^2$, respectively, for these sBBHs.