Near-IR Weak-lensing (NIRWL) Measurements in the CANDELS Fields. II. Mass Mapping and Overdensity Characterization

The Hubble Space Telescope Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) fields offer an exceptional combination of depth, spatial resolution, and area for identifying a shear-selected sample of dark matter overdensities. We present the first near-infrared (NIR) weak-lensing (WL) analysis of the 0.23 square degrees covered by the HST CANDELS fields: COSMOS, UDS, EGS, GOODS-N, and GOODS-S. Leveraging the high sensitivity of HST NIR imaging to distant galaxies, we achieve a WL source galaxy density of $\sim170$ galaxies arcmin$^{-2}$. Our analysis identifies 12 shear-selected overdensities spanning masses from $M_{200}=(0.2$--$2.2)\times10^{14}\ M_\odot$, with a median mass of $M_{200}=5.5\times10^{13}\ M_\odot$, demonstrating the strong capability of NIR WL for measuring low-mass systems. The systems lie in the redshift range $0.22<z<0.9$, with a mean redshift of $z=0.68$. We utilize multiwavelength data to confirm the nature of the overdensities. Seven of the overdensities have diffuse X-ray emission reported in the literature, with X-ray centroids that are spatially consistent with our WL peaks, confirming their nature as collapsed structures. We find that our WL detections broadly follow the expected X-ray luminosity--WL mass scaling relations. By stacking the tangential shear of all detections, we determine the average radial mass density profile and find that it is well fit by an NFW model with fitted concentration and mass of $4.9\pm2.1$ and $M_{200}=1.3\pm0.3\times10^{14}\ M_\odot$, respectively. These results serve as a precursor to NIR WL science with the Roman High Latitude Wide Area Survey.