2024ApJ...961...17R

We present the first test of coasting cosmological models with gravitational-wave (GW) standard sirens observed in the first three observing runs of the LIGO-Virgo-KAGRA detector network. We apply the statistical galaxy catalog method adapted to coasting cosmologies and infer constraints on the H₀ Hubble constant for the three fixed values of the curvature parameter $k=\left\{-1,0,+1\right\}$ in ${H}_{0}^{2}{c}^{-2}$ units. The maximum posteriors and 68.3% highest density intervals we obtained from a combined analysis of 46 dark siren detections and a single bright siren detection are ${H}_{0}=\left\{{68.1}_{-5.6}^{+8.5},{67.5}_{-5.2}^{+8.3},{67.1}_{-5.8}^{+6.6}\right\}\,\mathrm{km}\ {{\rm{s}}}^{-1}\ {\mathrm{Mpc}}^{-1}$, respectively. All our constraints on H₀ are consistent within 1σ with the H₀ measured with the differential age method, which provides a constraint on H₀ in coasting cosmologies independently from k. Our results constrain all cosmological models with a(t) ∝ t linear expansion in the luminosity distance and redshift range of the 47 LIGO-Virgo detections, i.e., d_L ≲ 5Gpc and z ≲ 0.8, which practically include all (both strictly linear and quasi-linear) models in the coasting model family. As we have found, the coasting models and the Lambda cold dark matter (or ΛCDM) model fit equally well to the applied set of GW detections.