Mapping the cosmic mass distribution with stacked weak gravitational lensing and Doppler lensing

TL;DR

This paper combines weak gravitational and Doppler lensing effects, using advanced simulations and ray-tracing, to map the universe's mass distribution around cosmic voids and halos, highlighting optimal redshift ranges for future surveys.

Contribution

It introduces a new approach integrating gravitational and Doppler lensing with relativistic N-body simulations to improve cosmic mass mapping.

Findings

Optimal redshift range for combined lensing signals is 0.3-0.4.

Stacking lensing signals enhances detection of mass distribution.

Future surveys should target these redshifts for better cosmological insights.

Abstract

Dark matter halos represent the highest density peaks in the matter distribution. Conversely, cosmic voids are under-dense patches of the universe. Probing the mass distribution of the universe requires various approaches, including weak gravitational lensing that subtly modifies the shape of distant sources, and Doppler lensing that changes the apparent size and magnitude of objects due to peculiar velocities. In this work, we adopt both gravitational and Doppler lensing effects to study the underlying matter distribution in and around cosmic voids/halos. We use the relativistic $N$-body code \texttt{gevolution}, to generate the mass perturbations and develop a new ray-tracing code that relies on the design of the ray bundle method. We consider three categories of halo masses and void radii, and extract the cosmological information by stacking weak-lensing and Doppler lensing signals around voids/halos. The results of this paper show that the most optimal strategy that combines both gravitational and Doppler lensing effects to map the mass distribution should focus on the redshift range $z\approx 0.3-0.4$. The recommendation of this paper is that future spectroscopic surveys should focus on these redshifts and utilise the gravitational and Doppler lensing techniques to extract information about underlying matter distribution across the cosmic web, especially inside cosmic voids. This could provide a complimentary cosmological analysis for ongoing or future low-redshift spectroscopic surveys.