Coasting Cosmologies Slightly Favor Large-Scale Structure Growth Data

Astronomy

Coasting Cosmologies Slightly Favor Large-Scale Structure Growth Data

Comparing coasting cosmologies and ΛCDM using large-scale structure data

From

Arxiv

This study derives formulas for cosmic growth in coasting universes where expansion is linear in time, and tests these models against observational data up to redshift 2. The coasting models fit the data well and slightly outperform the standard ΛCDM model in explaining the growth rate measurements.

Why it matters: Coasting cosmologies offer an alternative to ΛCDM that fits growth data and may address tensions in cosmic structure measurements.

The big picture: Four models—three coasting with different curvature and one ΛCDM—were compared using growth rate data and statistical tests.

Stunning stat: Coasting models have log-Bayes factors up to 0.272 favoring them over ΛCDM, with matter density Ωₘ around 0.2–0.4.

The stakes: The S₈ tension with Planck data persists but is slightly less severe in coasting models compared to ΛCDM's 2.00σ discrepancy.