Forecast for cosmological parameter estimation with gravitational-wave standard sirens from the LISA-Taiji network

TL;DR

This paper forecasts the potential of the LISA-Taiji gravitational-wave network to improve cosmological parameter estimation, especially for dark energy and Hubble constant, through simulated standard siren observations.

Contribution

It introduces a simulation framework for LISA-Taiji standard siren data and demonstrates its improved constraints on cosmological parameters compared to single missions.

Findings

LISA-Taiji network nearly doubles electromagnetic counterpart detections.

Standard sirens from LISA-Taiji can constrain H0 to 1.3% precision.

Combined GW-EM data can constrain dark energy equation of state to about 4%.

Abstract

LISA and Taiji are expected to form a space-based gravitational-wave (GW) detection network in the future. In this work, we make a forecast for the cosmological parameter estimation with the standard siren observation from the LISA-Taiji network. We simulate the standard siren data based on a scenario with configuration angle of $40^{\circ}$ between LISA and Taiji. Three models for the population of massive black hole binary (MBHB), i.e., pop III, Q3d, and Q3nod, are considered to predict the events of MBHB mergers. We find that, based on the LISA-Taiji network, the number of electromagnetic (EM) counterparts detected is almost doubled compared with the case of single Taiji mission. Therefore, the LISA-Taiji network's standard siren observation could provide much tighter constraints on cosmological parameters. For example, solely using the standard sirens from the LISA-Taiji network, the constraint precision of $H_0$ could reach $1.3\%$. Moreover, combined with the CMB data, the GW-EM observation based on the LISA-Taiji network could also tightly constrain the equation of state of dark energy, e.g., the constraint precision of $w$ reaches about $4\%$, which is comparable with the result of CMB+BAO+SN. It is concluded that the GW standard sirens from the LISA-Taiji network will become a useful cosmological probe in understanding the nature of dark energy in the future.