AGN 8GHz measurements

We also explored how astrophysical parameters depend on fixed cosmological models with different Omega_m_ values. The randomization test showed that the posterior distributions from randomized data do not overlap with those from real observations, with significant deviations, confirming that the measured angular size-redshift relation is physically meaningful and not a chance alignment. The astrophysical model parameter that describes the redshift dependence of the source angular size exhibits strong sensitivity and degeneracy with Omega_m_.

Simulated mock catalogues indicate that the method is able to constrain Omega_m_ if the data scatter is below ~20%, but current real data noise levels are too high for reaching competitive cosmological constraints. Scaling estimates suggest that high-quality data of samples of several thousands to ~100000 sources, a standardization calibration approach, and/or refining sample selection criteria are needed to fully exploit the potential of the angular size- redshift test with this type of object.