S8 increases with effective redshift in ΛCDM cosmology

Shahnawaz A. Adil

doi:10.1093/mnrasl/slad165

S8 increases with effective redshift in ΛCDM cosmology

2023-11-03

8

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AI

M. M. Sheikh-Jabbari *

DOI：10.1093/mnrasl/slad165

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Hubble constant H-0 and weighted amplitude of matter fluctuations S-8 determinations are biased to higher and lower values, respectively, in the late universe with respect to early universe values inferred by the Planck collaboration within flat Lambda CDM cosmology. If these anomalies are physical, that is, not due to systematics, they naively suggest that H-0 decreases and S-8 increases with effective redshift. Here, subjecting matter density today Omega(m) to a prior, corresponding to a combination of Planck CMB and BAO data, we perform a consistency test of the Planck-Lambda CDM cosmology and show that S-8 determinations from f sigma(8) (z) constraints increase with effective redshift. Due to the redshift evolution, a similar to 3 sigma tension in the S-8 parameter with Planck at lower redshifts remarkably becomes consistent with Planck within 1 sigma at high redshifts. This provides corroborating support for an S-8 discrepancy that is physical in origin. We further confirm that the flat Lambda CDM model is preferred over a theoretically ad hoc model with a jump in S-8 at a given redshift. In the absence of the CMB+BAO Omega(m) prior, we find that >3 sigma tensions with Planck in low-redshift data are ameliorated by shifts in the parameters in high-redshift data. Results here and elsewhere suggest that the Lambda CDM cosmological parameters are redshift dependent. Fitting parameters that evolve with redshift is a recognizable hallmark of model breakdown.

Keyword:

(cosmology:) cosmological parameters

(cosmology:) large-scale structure of Universe

S8 increases with effective redshift in ΛCDM cosmology

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