摘要:
   UNIONS, the Ultra-violet Near-infrared Optical Northern Survey is a wide-field multi-band imaging survey using telescopes on Hawai'i to cover 4,800 square degrees in the Northern hemisphere. Data in the r-band is taken with the Canada-France Hawai'i Telescope. The excellent image quality and observing conditions make these data ideal for weak gravitational lensing studies. In this talk I will show first lensing results from the UNIONS survey, obtained with the dedicated weak-lensing pipeline ShapePipe. I will present cross-correlation measurements of weak lensing with foreground objects, to better understand the relation between dark matter and baryonic tracers. These include constraints on the masses and shapes of dark-matter halos aorund galaxy groups and clusters, as well as the density profiles of cosmic voids. In addition, I will present measurements of intrinsic alignments of galaxies in their dark-matter environment. I will end with preliminary constraints on cosmological parameters from weak-lensing peak counts.