Revealing intrinsic flat ΛcDM biases with standardizable candles

Emerging high-redshift cosmological probes, in particular quasars (QSOs), show a preference for larger matter densities, ωm≈1, within the flat ΛCDM framework. Here, using the Risaliti-Lusso relation for standardizable QSOs, we demonstrate that the QSOs recover the same Planck-ΛCDM universe as type Ia supernovae (SN), ωm≈0.3 at lower redshifts 0<z≲0.7, before transitioning to an Einstein-de Sitter universe (ωm=1) at higher redshifts z≳1. We illustrate the same trend, namely increasing ωm and decreasing H0 with redshift, in SN but poor statistics prevent a definitive statement. We explain physically why the trend may be expected and show the intrinsic bias through non-Gaussian tails with mock SN data. Our results highlight an intrinsic bias in the flat ΛCDM universe, whereby ωm increases, H0 decreases and S8 increases with effective redshift, thus providing a new perspective on ΛCDM tensions; even in a Planck-ΛCDM universe the current tensions may be expected.