Bayesian parameter estimation of massive black hole binaries with TianQin-LISA

This paper analyses the impact of various parameter changes on the estimation of parameters for massive black hole binary (MBHB) systems using a Bayesian inference technique. Several designed MBHB systems were chosen for comparison with a fiducial system to explore the influence of parameters such as sky location, inclination angle, anti-spin, large mass ratio and light mass. And the two reported MBHB candidates named OJ287 and Tick-Tock are also considered. The study found that the network of TianQin and LISA can break certain degeneracies among different parameters, improving the estimation of parameters, particularly for extrinsic parameters. Meanwhile, the degeneracies between different intrinsic parameters are highly sensitive to the value of the parameters. Additionally, the small inclination angles and limited detection of the inspiral phase can introduce significant bias in the estimation of parameters. The presence of instrument noise will also introduce bias and worsen the precision. The paper concludes that the network of TianQin and LISA can significantly improve the estimation of extrinsic parameters by about one order of magnitude while yielding slight improvements in the intrinsic parameters. Moreover, parameter estimation can still be subject to biases even with a sufficiently high signal-to-noise ratio if the detected signal does not encompass all stages of the inspiral, merger, and ringdown.