Cosmological constraints from type-I radio-loud quasars

We obtain a sample of 1192 type-I quasars with the UV-optical, radio, and x-ray waveband coverage, which combined with the data from Huang and Chang [Mon. Not. R. Astron. Soc. 515, 1358 (2022), 10.1093/mnras/stac1451] and other matching objects of SDSS-DR16 with FIRST, XMM-Newton, and Chandra Source Catalog, and a sample of 407 flat-spectrum radio-loud quasars of blazars from the Roma-BZCAT, which can be used to investigate their multiband luminosity correlations and measure the luminosity distances of these type-I radio-loud quasar (RLQ) samples. We check the correlation between x-ray, UV-optical, and radio luminosity for various groupings of radio-quiet quasars (RQQs) and RLQs by parametrizing x-ray luminosity as a sole function of UV-optical or radio luminosity and as a joint function of UV/optical radio luminosity, which also can be employed to determine these cosmological distances. By Bayesian information criterion, the data suggest that the x-ray luminosity of RQQs is indirectly correlative with radio luminosity because of the connection between UV-optical and radio luminosity. However for RLQs, the x-ray luminosity is directly related to radio luminosity, and the correlations between x-ray, optical/UV, and radio luminosity get stronger with the increase in the ratio of monochromatic luminosities. Furthermore, we compare the results from RLQs with different UV-optical power-law index Γ_UV, and find that the goodness of fit for RLQs with Γ_UV≤1.6 is tentatively better. Finally, we apply a combination of type-I RLQs and Type Ia supernova (SN Ia) Pantheon to verify the nature of dark energy concerning whether or not its density deviates from the constant, and the statistical results indicate that the Lambda cold dark matter model may be in tension with type-I RLQs at ∼1.5 σ .