A gravitational lensing detection of filamentary structures connecting luminous red galaxies

TL;DR

This paper reports a weak lensing detection of filamentary structures in the cosmic web connecting luminous red galaxies, revealing their average density and confirming their presence through shear measurements.

Contribution

First weak lensing detection of cosmic web filaments connecting luminous red galaxies using combined survey data.

Findings

3.4 sigma detection of shear signal from filaments

Average filament density is 15 ± 4 times the critical density

Method combines multiple survey data for filament detection

Abstract

We present a weak lensing detection of filamentary structures in the cosmic web, combining data from the Kilo-Degree Survey, the Red Cluster Sequence Lensing Survey and the Canada-France-Hawaii Telescope Lensing Survey. The line connecting luminous red galaxies with a separation of $3 - 5\, h^{-1}\text{Mpc}$ is chosen as a proxy for the location of filaments. We measure the average weak lensing shear around $\sim$11,000 candidate filaments selected in this way from the Sloan Digital Sky Survey. After nulling the shear induced by the dark matter haloes around each galaxy, we report a $3.4\,\sigma$ detection of an anisotropic shear signal from the matter that connects them. Adopting a filament density profile, motivated from $N$-body simulations, the average density at the centre of these filamentary structures is found to be $15 \pm 4$ times the critical density.