Tracing Astrophysical Black Hole Seeds and Primordial Black Holes with LISA-Taiji Network

TL;DR

This paper explores how the combined LISA-Taiji network enhances detection and parameter estimation of astrophysical and primordial black holes, especially at high redshifts and lower masses, compared to individual detectors.

Contribution

It demonstrates that the joint LISA-Taiji network improves detection capabilities and parameter estimation for black hole seeds across different formation scenarios.

Findings

Joint network can observe light seeds at 15<z<20, unlike single detectors.

Enhanced signal-to-noise ratio for heavy seed detection.

Better parameter estimation with Fisher matrix analysis.

Abstract

In this work, we discuss the improvement that the joint network of LISA and Taiji could provide on exploring two kinds of black hole formation mechanisms. For astrophysical origin, we consider light seed and heavy seed scenarios, and generate populations accordingly. We find that the joint network has the potential to observe growing light seeds in the range 15 < z < 20, while single detector can hardly see, which would shed light on the light seeding mechanism. For the heavy seeds, the joint network only improves the signal-to-noise ratio. For primordial origin, we calculate the event rate at z > 20 and detection rates of LISA and the joint network. The joint network expands LISA's horizon towards lower mass end, where the event rate is high, so we have better chance observing primordial black holes with the joint network. We also estimate the parameters using Fisher matrices of LISA and the joint network, and find that the joint network significantly improves the estimation.