Massive Black Hole Binaries and Where to Find Them with Dual Detector Networks

A single space-based gravitational wave detector will push the boundaries of astronomy and fundamental physics. Having a network of two or more detectors would significantly improve source localization. Here we consider how dual networks of space-based detectors would improve parameter estimation of massive black hole binaries. We consider two scenarios: a network comprised of the Laser Interferometer Space Antenna (LISA) and an additional LISA-like heliocentric detector (e.g. Taiji); and a network comprised of LISA with an an additional geocentric detector (e.g. TianQin). We use Markov chain Monte Carlo techniques and Fisher matrix estimates to explore the impact of a two detector network on sky localization and distance determination. The impact on other source parameters is also studied. With the addition of a Taiji or TianQin, we find orders of magnitude improvements in sky localization for the more massive MBHBs, while also seeing improvements for lower mass systems, and for other source parameters.