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

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 thecosmological parameter estimation with the standard siren observation from theLISA-Taiji network. We simulate the standard siren data based on a scenariowith configuration angle of $40^{\circ}$ between LISA and Taiji. Three modelsfor the population of massive black hole binary (MBHB), i.e., pop III, Q3d, andQ3nod, 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 Taijimission. Therefore, the LISA-Taiji network's standard siren observation couldprovide much tighter constraints on cosmological parameters. For example,solely using the standard sirens from the LISA-Taiji network, the constraintprecision 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 tightlyconstrain the equation of state of dark energy, e.g., the constraint precisionof $w$ 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 willbecome a useful cosmological probe in understanding the nature of dark energyin the future.