A new stochastic approach to cumulative weak lensing

TL;DR

This paper introduces a stochastic method to model weak gravitational lensing by dark matter halos, enabling quick calculations of magnification effects and their impact on cosmological measurements, with a practical software tool provided.

Contribution

A novel stochastic approach for calculating weak lensing magnification distributions, including a fast Mathematica code implementation.

Findings

Large-scale inhomogeneities can bias supernova magnitude measurements.

The method allows rapid computation of lensing effects for various universe models.

Potential biases in cosmological parameters from current supernova data are highlighted.

Abstract

We study the weak gravitational lensing effects caused by a stochastic distribution of dark matter halos. We develop a simple approach to calculate the magnification probability distribution function which allows us to easily compute the magnitude bias and dispersion for an arbitrary data sample and a given universe model. As an application we consider the effects of single-mass large-scale cosmic inhomogeneities to the SNe magnitude-redshift relation, and conclude that such structures could bias the PDF enough to affect the extraction of cosmological parameters from the limited size of present-day SNe data samples. We also release turboGL, a simple and very fast (<= 1s) Mathematica code based on the method here presented.