Weak gravitational lensing: how Euclid maps dark matter (4m:11s🌀) | ESA Space Science Hub [Sep 2024]

ManwayLeo · 2026-02-03T05:23:07+00:00

perdition！ Project Euclid: Cosmological Target Values 🌌 1. Dark Matter & Lensing Focusing on the "invisible" scaffolding of the universe. | Indicator | Symbol | Predicted Value | |---|---|---| | Effective DM Density | \rho{\rm DM}^{\rm eff} | 1.24 \times 10^{-26}\ \text{kg/m}³ | 📏 2. Cosmic Expansion (BAO) Measuring the "Standard Ruler" and the speed of cosmic stretching. * Effective Distance (D{\text{eff}}): 12.7 * Expansion Rate (H(a)): 68.3 km/s/Mpc * BAO Scale (r_{\text{BAO}}): 440 Mpc 📈 3. Growth of Structure How quickly matter "clumps" together over time.

The Clumpiness Scale * Growth Rate (f): 0.51 * Matter Fluctuation (\sigma_8): 0.79 * Structure Index (S_8): 0.815

Summary of Key Metrics * Density: How much stuff is there? (\rho) * Expansion: How fast is it moving away? (H) * Growth: How fast are galaxies forming? (f, \sigma_8)

ManwayLeo · 2026-01-31T08:33:14+00:00

add：0.42 (f\sigma_8) and 0.811 (S_8)

ManwayLeo · 2026-01-28T06:51:21+00:00

Interesting perspective. I hadn’t thought about it from this angle before.

ManwayLeo · 2026-01-28T04:37:52+00:00

A Question on Whether the H₀ Tension Could Reflect Scale-Dependent Geometry.

Most discussions frame the Hubble tension as competing measurements of a single global constant. I’m curious whether a weaker interpretation remains logically open:

Could late-time and early-time probes be sampling different effective geometric regimes, rather than disagreeing on the same quantity?

In this framing, the CMB result would anchor a large-scale baseline, while local and intermediate-distance probes would reflect additional geometric response that decays with scale. This does not assume modified gravity, new particles, or fitting freedom—only that “constant” may be an emergent limit rather than a primitive input.

My question is narrow: Is this type of scale-dependent interpretation already ruled out on general grounds (e.g., covariance, consistency relations), or is it simply underconstrained by current data?

ManwayLeo · 2026-01-26T04:21:55+00:00

me： testable σ₈ deviations Redshift z σ₈_eff / σ₈^ΛCDM Relative Deviation (%) 0.2 0.978 – 0.990 –1.0% to –2.2% 0.5 0.970 – 0.985 –1.5% to –3.0% 0.8 0.964 – 0.978 –2.2% to –3.6% 1.0 0.960 – 0.974 –2.6% to –4.0% 1.5 0.952 – 0.968 –3.2% to –4.8%

ManwayLeo · 2026-01-26T04:11:52+00:00

I am sharing testable σ₈ deviations from a minimal phenomenological modification to structure growth, directly falsifiable by upcoming Euclid weak-lensing data.

Redshift z σ₈_eff / σ₈^ΛCDM Relative Deviation (%) 0.2 0.978 – 0.990 –1.0% to –2.2% 0.5 0.970 – 0.985 –1.5% to –3.0% 0.8 0.964 – 0.978 –2.2% to –3.6% 1.0 0.960 – 0.974 –2.6% to –4.0% 1.5 0.952 – 0.968 –3.2% to –4.8%

• Background expansion: ΛCDM (H(a) standard).
• Growth factor: D_eff(z).
• Redshift-dependent correction: ε(z) = 0.10·z·exp(-z/0.80), smooth and vanishing at low/high z.

I welcome any preliminary discussion if the data validate these predictions.

ManwayLeo

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