Vol. 633
Sect. 3. Cosmology

A gravitational lensing detection of filamentary structures connecting luminous red galaxies

by Q. Xia, N. Robertson, C. Heymans, et al. 2020, A&A, 633, A89

In this cosmic web, large under-dense regions (voids) are enclosed by anisotropically collapsed surface structures (sheets) and line structures (filaments) which intersect at the most overdense isotropic regions (clusters). Simulations predict that as much as 40% of the mass in the Universe should be located in filaments, however, its detection poses a great challenge. Filaments have been detected by Xray emission and, recently, by the SZ signal. In this paper, the authors investigate the use of weak gravitational lensing to detect their presence combining three large public weak lensing surveys: KIDS+VIKING, RCSLenS, and the CFHTLenS to improve upon previous methodologies with the help of N-body simulations. As a result, they find a 3.4 σ detection of filamentary structure connecting luminous red galaxies separated by 3 − 5 h−1 Mpc, while they do not detect significant signals for larger separations, which is contrary to previous claims. The average density at the centre of these filamentary structures is found to be 15 ± 4 times the critical density.