We use weak lensing observations to make the first measurement of the characteristic depletion radius, one of the three radii that characterize the region where matter is being depleted by growing haloes. The lenses are taken from the halo catalog produced by the extended halo-based group/cluster finder applied to DESI Legacy Imaging Surveys DR9, while the sources are extracted from the DECaLS DR8 imaging data with the Fourier_Quad pipeline. We study halo masses 12 < log (Mgrp [M⊙/h]) ≤ 15.3 within redshifts 0.2 ≤ z ≤ 0.3. The virial and splashback radii are also measured and used to test the original findings on the depletion region. When binning haloes by mass, we find consistency between most of our measurements and predictions from the CosmicGrowth simulation, with exceptions to the lowest mass bins. The characteristic depletion radius is found to be roughly 2.5 times the virial radius and 1.7 − 3 times the splashback radius, in line with an approximately universal outer density profile, and the average enclosed density within the characteristic depletion radius is found to be roughly 29 times the mean matter density of the Universe in our sample. When binning haloes by both mass and a proxy for halo concentration, we do not detect a significant variation of the depletion radius with concentration, on which the simulation prediction is also sensitive to the choice of concentration proxy. We also confirm that the measured splashback radius varies with concentration differently from simulation predictions.

Based on independent shear measurements using the Dark Energy Camera Legacy Survey/DR8 imaging data, we measure the weak lensing signals around isolated central galaxies (ICGs) from Sloan Digital Sky Survey/DR7 at z ∼ 0.1. The projected stellar mass density profiles of satellite galaxies are further deduced, using photometric sources from the Hyper Suprime-cam survey. The signals of ICGs + their extended stellar halos are taken from Wang et al. All measurements are compared with predictions by the IllustrisTNG300-1 simulation. We find, overall, a good agreement between observation and TNG300. In particular, a correction to the stellar mass of massive observed ICGs is applied based on the calibration of He et al., which brings a much better agreement with TNG300 predicted lensing signals at log 10 M * / M ⊙ > 11.1 . In real observation, red ICGs are hosted by more massive dark matter halos and have more satellites and more extended stellar halos than blue ICGs at fixed stellar mass. However, in TNG300 there are more satellites around blue ICGs at fixed stellar mass, and the outer stellar halos of red and blue ICGs are similar. The stellar halos of TNG galaxies are more extended compared with real observed galaxies, especially for blue ICGs with log 10 M * / M ⊙ > 10.8 . We find the same trend for TNG100 galaxies and for true halo central galaxies. The tensions between TNG and real galaxies indicate that satellite disruptions are stronger in TNG. In both TNG300 and observation, satellites approximately trace the underlying dark matter distribution beyond 0.1R 200, but the fraction of total stellar mass in TNG300 does not show the same radial distribution as real galaxies.