Prospects for constraining interacting dark energy cosmology with gravitational-wave bright sirens detected by future FAST/SKA-era pulsar timing arrays

Abstract

We explore the constraints on cosmological parameters in interacting dark energy (IDE) models with energy transfer rates Q = βH ρde and Q = βH ρc, using simulated gravitational-wave (GW) bright sirens data from pulsar timing array (PTA) and Planck 2018 cosmic microwave background (CMB) data. By incorporating the mock PTA data from future observations in the FAST/SKA era, we demonstrate significant improvements on the constraint precision of key cosmological parameters such as the Hubble constant H0, matter density Ωm, and the coupling parameter β. In the IDE model with Q = βH ρde, PTA data could provide tighter constraints on these parameters than CMB data, particularly due to the high sensitivity of GW standard sirens in probing the late universe. Combination of PTA and CMB data could lead to the constraint improvements of 37.4% for H0, 37.4% for Ωm, and 36.1% for β, compared to the case using CMB data alone. In contrast, for the IDE model with Q = βH ρc, the CMB data alone could provide tighter constraints on ρ compared with PTA data, due to the stronger effect of CMB in the early universe. Combination of PTA and CMB data still yields constraint improvements of 17.6% for H0, 24.3% for Ωm and 17.4% for β compared to the case using CMB data alone. With the increase of the number of millisecond pulsars (MSPs), the constraints on all parameters for both IDE models can be further enhanced. Our results highlight the potential of future PTA observations to significantly improve the cosmological parameter estimation in IDE models, offering crucial insights into the nature of dark energy and the interaction between dark sectors.