Standard siren cosmology with the LISA-Taiji network

Gravitational waves(GWs)are a marvelous prediction of general relativity.The GW waveform from a compact binary coalescence is theoretically predictable,and different binary systems emit GWs in different frequency bands.The frequencies of GWs emitted by stellar-mass binaries fall within the detection band of ground-based detectors(10-10⁴Hz).GWs at lower frequencies(10^-4-1 Hz)emitted by massive black hole binaries(MBHBs)have wavelengths larger than the earth itself.Deploying a GW detector large enough to efficiently detect them requires going to space.