Gravitational wave standard sirens from GWTC-3 combined with DESI DR2 and DESY5: A late-universe probe of the Hubble constant and dark energy

TL;DR

The paper investigates a late-universe cosmology probe by combining GW standard sirens from GWTC-3 with DESI DR2 BAO and DESY5 SNe Ia to constrain $H_0$ and the dark-energy EoS in $\Lambda$CDM and $w_0w_a$CDM, while treating $r_d$ and $M_B$ as free parameters to avoid early-un Universe priors. Using 47 GW events, the authors perform hierarchical Bayesian inference that couples GW data with galaxy-based redshift priors and population models, alongside BAO and SNe Ia likelihoods within a unified framework. The joint GW+BAO+SNe Ia analysis yields $H_0=76.1^{+6.1}_{-11.5}$ km s$^{-1}$ Mpc$^{-1}$ and $\Omega_m=0.310\pm0.008$ in $\Lambda$CDM, and $H_0=74.8^{+6.3}_{-8.9}$ km s$^{-1}$ Mpc$^{-1}$, $\Omega_m=0.320^{+0.015}_{-0.012}$, $w_0=-0.775^{+0.072}_{-0.074}$, $w_a=-0.80\pm0.47$ in $w_0w_a$CDM, with a mild phantom-crossing of $w(z)$ around $z\sim0.5$ at 1$\sigma$. The results demonstrate that GW standard sirens can break degeneracies with $r_d$ and $M_B$, and that the combined late-universe dataset provides meaningful, CMB- and distance-ladder-independent constraints on $H_0$ and dark energy, supporting a non-constant EoS at modest significance.

Abstract

Recently, the combination of the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2) baryon acoustic oscillation (BAO) data and the Planck cosmic microwave background (CMB) measurements has shown a $\sim$3$σ$ preference for a dynamical dark energy model with a phantom-crossing behavior. However, such a phantom-crossing dark energy evolution further exacerbates the already severe Hubble tension in the $Λ$CDM model. Moreover, there exists a $\sim2σ$ tension between the DESI DR2 BAO and CMB datasets. Therefore, it is essential to measure the Hubble constant and dark-energy equation-of-state (EoS) parameters using only late-universe observations. In this work, we investigate a novel late-universe data combination: gravitational-wave (GW) standard sirens, BAO, and Type Ia supernovae (SNe Ia). This combination provides a fully distance-ladder- and CMB-independent determination of the Hubble constant and the dark-energy EoS. Using 47 GW standard sirens from the third Gravitational-Wave Transient Catalog, the DESI DR2 BAO data, and DESY5 SNe Ia data, in the $w_0w_a$CDM model, we obtain $H_0=74.8^{+6.3}_{-8.9}$ km s$^{-1}$ Mpc$^{-1}$, $Ω_{\rm m}=0.320^{+0.015}_{-0.012}$, $w_0=-0.775^{+0.072}_{-0.074}$, and $w_a=-0.80\pm0.47$, indicating a mild phantom-crossing behavior within the $1σ$ credible interval with an $H_0$ value consistent with the distance ladder measurements. Our analysis demonstrates the power of GW standard sirens in breaking parameter degeneracies, and this novel data combination provides joint constraints on the Hubble constant and the dark-energy EoS parameters.

Figures (3)

• Figure 1: Posterior distributions (68$\%$ and 95$\%$ credible regions) of $H_0$, $r_{\rm d}$, $M_B$, and $\Omega_{\mathrm{m}}$ in the $\Lambda$CDM model, obtained from GW, SNe Ia, BAO, BAO+SNe Ia, and GW+BAO+SNe Ia data.
• Figure 2: Posterior distributions (68$\%$ and 95$\%$ credible regions) of $H_0$, $\Omega_{\mathrm{m}}$, $w_0$, and $w_a$ in the $w_0w_a$CDM model, obtained from GW, SNe Ia, BAO, BAO+SNe Ia, and GW+BAO+SNe Ia data.
• Figure 3: The dark energy EoS across the redshift. The blue lines represent the results of GW+BAO+SNe Ia in the $w_0w_a$CDM model, with the blue and light blue shadow regions indicating the 68$\%$ and 95$\%$ credible regions. The green line represents the situation of the $\Lambda$CDM model with $w=1$.