Accurate relativistic observables from post-processing light cone catalogues

TL;DR

This paper presents a new post-processing scheme, LC-Metric, that accurately constructs relativistic observables from light cone data, enabling precise modeling of nonlinear general relativistic effects in cosmology.

Contribution

The paper introduces LC-Metric, a novel approach to derive the spacetime metric from light cone data, improving the accuracy of relativistic cosmological observables.

Findings

High-precision metric determination from light cone data

Accurate modeling of lensing convergence signals

Order of magnitude improvement in ISW effect quantification

Abstract

We introduce and study a new scheme to construct relativistic observables from post-processing light cone data. This construction is based on a novel approach, LC-Metric, which takes general light cone or snapshot output generated by arbitrary N-body simulations or emulations and solves the linearized Einstein equations to determine the spacetime metric on the light cone. We find that this scheme is able to determine the metric to high precision, and subsequently generate accurate mock cosmological observations sensitive to effects such as post-Born lensing and nonlinear ISW contributions. By comparing to conventional methods in quantifying those general relativistic effects, we show that this scheme is able to accurately construct the lensing convergence signal. We also find the accuracy of this method in quantifying the ISW effects in the highly nonlinear regime outperforms conventional methods by an order of magnitude. This scheme opens a new path for exploring and modeling higher-order and nonlinear general relativistic contributions to cosmological observables, including mock observations of gravitational lensing and the moving lens and Rees-Sciama effects.