Detection of the stochastic gravitational wave background with the space-borne gravitational-wave detector network

Abstract: The stochastic gravitational wave background (SGWB) is one of the main detection targets for future millihertz space-borne gravitational-wave observatories such as the \ac{LISA}, TianQin, and Taiji. For a single LISA-like detector, a null-channel method was developed to identify the SGWB by integrating data from the A and E channels with a noise-only T channel. However, the noise monitoring channel will not be available if one of the laser interferometer arms fails. By combining these detectors, it will be possible to build detector networks to search for SGWB via cross-correlation analysis.In this work, we developed a Bayesian data analysis method based on \ac{TDI} Michelson-type channel. We then investigate the detectability of the TianQin-LISA detector network for various isotropic SGWB. Assuming a three-month observation, the TianQin-LISA detector network could be able to confidently detect SGWB with energy density as low as $\Omega_{\rm PL} = 6.0 \times 10^{-13}$, $\Omega_{\rm Flat} = 2.0 \times 10^{-12}$ and $\Omega_{\rm SP} = 1.2 \times 10^{-12}$ for power-law, flat and single-peak models, respectively.