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Paper   IPM / P / 17096
School of Physics
  Title:   Revealing intrinsic flat ΛCDM biases with standardizable candles
1.  E. O. Colgain
2.  M.M. Sheikh-Jabbari
3.  R. Solomon
4.  G. Bargiacchi
5.  S. Capozziello
  Status:   Published
  Journal: Phys. Rev. D
  No.:  4
  Vol.:  106
  Year:  2022
  Pages:   L041301
  Supported by:  IPM
Emerging high redshift cosmological probes, in particular quasars (QSOs), show a preference for larger matter densities, $\Omega_{m} \approx 1$, within the flat $\Lambda$CDM framework. Here, using the Risaliti-Lusso relation for standardizable QSOs, we demonstrate that the QSOs recover the \textit{same} Planck-$\Lambda$CDM Universe as Type Ia supernovae (SN), $\Omega_m \approx 0.3$ at lower redshifts $ 0 < z \lesssim 0.7$, before transitioning to an Einstein-de Sitter Universe ($\Omega_m =1$) at higher redshifts $z \gtrsim 1$. We illustrate the same trend, namely increasing $\Omega_{m}$ and decreasing $H_0$ 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 $\Lambda$CDM Universe, whereby $\Omega_m$ increases, $H_0$ decreases and $S_8$ increases with effective redshift, thus providing a new perspective on $\Lambda$CDM tensions; even in a Planck-$\Lambda$CDM Universe the current tensions may be expected.

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