Published January 1, 2025 | Version v1
Journal article Open

Further support for <i>S</i><sub>8</sub> increasing with effective redshift

  • 1. Istanbul Tech Univ, Dept Phys, TR-34469 Istanbul, Turkiye
  • 2. Atlantic Technol Univ, Sch Sci, Ash Lane, Sligo F91 YW50, Ireland
  • 3. Jamia Millia Islamia, Dept Phys, New Delhi 110025, India
  • 4. Inst Res Fundamental Sci IPM, Sch Phys, POB 19395-5531, Tehran, Iran

Description

We previously reported an increasing trend in S-8 with effective redshift z(eff) based on f sigma(8)(z) constraints over the redshift range 0 less than or similar to z less than or similar to 2. Recently, independent studies presenting data that aligns with the expected trends have appeared. Here, we quantify the statistical significance of the increasing S-8 trends in these newer studies by fitting a linear model for the slope Delta S-8/Delta z(eff) and comparing to mock simulations. We find probabilities of p = 0.0163 and p = 0.0185, corresponding to approximately 2.1 sigma for each data set. The studies overlap in their use of DESI Legacy Survey data, but in one study the role of optical data is to mitigate systematics by removing contaminants from the pipeline. On the plausible assumption that correlations are negligible, we use Fisher's method to combine the independent probabilities and obtain p = 0.0027 (2.8 sigma). When we incorporate earlier findings, the combined statistical significance reaches between 3 sigma and 3.7 sigma. Finally, we discuss how 'scatter' in sigma(8)/S-8 constraints from recent DESI full-shape galaxy clustering fits this picture at low statistical significance. This letter continues a series of studies initiated in 2020 that explore redshift-dependent Lambda CDM parameters as an indication of model breakdown.

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