Reducing cosmological degeneracies by combining multiple classes of LISA gravitational-wave standard sirens

TL;DR

This paper demonstrates that combining different classes of LISA gravitational-wave standard sirens from various redshifts improves constraints on key cosmological parameters like the Hubble constant and dark energy properties.

Contribution

It introduces a joint analysis method for LISA's gravitational-wave sources across a broad redshift range, reducing degeneracies and enhancing cosmological parameter estimation.

Findings

Combined standard sirens improve constraints on H_0 and w_0.

Joint analysis reduces cosmological degeneracies.

LISA's potential for late-time cosmology is demonstrated.

Abstract

We present the first joint gravitational-wave cosmological inference with LISA extreme mass-ratio inspirals at $z\lesssim1$ (galaxy redshifts) and massive black hole binaries at $z\gtrsim1$ (electromagnetic counterparts). Combining these standard sirens reduces cosmological degeneracies and yields competitive constraints on the Hubble constant $H_0$ and the dark-energy equation-of-state parameter $w_0$. This highlights LISA's potential for late-time cosmology across a broad redshift range with systematics distinct from electromagnetic distance indicators.