A comparison of cosmological models with high-redshift quasars

The non-linear relationship between the monochromatic X-ray and UV luminosities in quasars offers the possibility of using high-z quasars as standard candles for cosmological testing. In this paper, we use a high-quality catalog of 1598 quasars extending to redshift ∼6, to compare the R h = ct and ΛCDM cosmological models which are the most debated. The quasar samples are mainly from the XMM-Newton and the Sloan Digital Sky Survey (SDSS). As we shall see, the Akaike Information Criterion favors ΛCDM over R h = ct with a relative likelihood of ∼ 86.35% versus ∼ 13.65%.