The Optical Expansion Scalar in Cosmological Perturbation Theory

arXiv:2609.30108 · astro-ph.CO · Submitted 2026-09-24 · Read on arXiv

astro-ph.CO

Submitted: 2026-09-24

Updated: 2026-09-24

Code: https://github.com/xfangcosmo/FFTLog-and-beyond

Terminology

• Weak Lensing — 8× in this paper · explained in 2 episodes
• Consistency — 7× in this paper · explained in 3 episodes
• Trace — 3× in this paper · explained in 2 episodes
• Gravitational Lensing — 2× in this paper · explained in 2 episodes
• N-body simulations — 2× in this paper · explained in 2 episodes
• Accuracy — 1× in this paper · explained in 1 episode
• Anisotropy — 1× in this paper · explained in 3 episodes
• Clustering — 1× in this paper · explained in 2 episodes
• Cosmic Microwave Background — 1× in this paper
• Rubin Legacy Survey of Space and Time — 1× in this paper

Sources

• Dark Energy Survey Year 6 Results: Cosmological Constraints from Cosmic Shear
• Large Synoptic Survey Telescope: Dark Energy Science Collaboration
• Euclid Definition Study Report
• Notes on gravitational wave amplitude evolution beyond null geodesics
• Model-independent constraints on generalized FLRW consistency relations with bootstrap-based symbolic regression
• LSST Science Book, Version 2.0
• Measuring the expansion history of the Universe with cosmic chronometers
• Lensing without mixing: Probing baryonic acoustic oscillations and other scale-dependent features in cosmic shear surveys
• KiDS-Legacy: Cosmological constraints from cosmic shear with the complete Kilo-Degree Survey
• Cosmology and Fundamental Physics with the Euclid Satellite
• The Pantheon+ Analysis: Cosmological Constraints
• The averaging problem on the past null cone in inhomogeneous dust cosmologies
• General relativity and cosmic structure formation
• Light propagation in inhomogeneous and anisotropic cosmologies
• A practical recipe for variable-step finite differences via equidistribution
• Multipole decomposition of the general luminosity distance 'Hubble law' -- a new framework for observational cosmology
• A general test of the Copernican Principle
• Diagnostic Consistency Tests of the Concordance Cosmology
• Effect of Peculiar Motion in Weak Lensing

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• Non-Gaussian Galaxy Stochasticity and the Noise-Field Formulation