General Relativistic Corrections to the Weak Lensing Convergence Power Spectrum

TL;DR

This paper calculates the weak lensing convergence power spectrum using full general relativistic simulations and compares it to approximate methods, revealing significant corrections at large scales.

Contribution

It introduces a fully relativistic approach to compute the weak lensing spectrum and quantifies the corrections compared to linearized Newtonian methods.

Findings

Corrections of about 10% at very large scales (ell ~ 2-3).

Percent-level corrections at intermediate scales (ell ~ 20-30).

Highlights importance of relativistic effects in weak lensing analyses.

Abstract

We compute the weak lensing convergence power spectrum, $C^{\kappa\kappa}(\theta)$, in a dust-filled universe using fully non-linear general relativistic simulations. The spectrum is then compared to more standard, approximate calculations by computing the Bardeen (Newtonian) potentials in linearized gravity and utilizing the Born approximation. We find corrections to the angular power spectrum amplitude of order ten percent at very large angular scales, $\ell ~ 2-3$, and percent-level corrections at intermediate angular scales of $\ell ~ 20-30$.