The COSMOS-Web Lens Survey (COWLS) II: depth, resolution, and NIR coverage from JWST reveal 17 spectacular lenses

The COSMOS-Web Lens Survey (COWLS) presents the first systematic search for strong gravitational lenses in the COSMOSWeb field using data from the James Webb Space Telescope (JWST). Using high-resolution NIRCam imaging, we visually inspected over 42 660 galaxies and identified over 400 lensing candidates. Here, we report the 17 most obvious and spectacular strong lensing systems, distinguished by large Einstein rings, arcs, and distinct lens and source colours. These diverse lenses, identified only through visual inspection of lens-light-subtracted images, represent the extremes of lens parameter space. Exceptionally high signal-to-noise, multi-wavelength imaging enables unprecedented lensing analysis, including ‘HST-dark’ source galaxies that are also invisible in deeper but bluer JWST wavebands: enabling clean deblending between the lens and the source. Some sources exhibit dramatic morphological changes across wavelengths, and patterns of dust absorption within lenses. No other current facility, including the Hubble Space Telescope, can discover or image such lenses with comparable detail. We estimate that JWST uncovers a new spectacular lens approximately every 10 to 12 NIRCam pointings, suggesting that over 40 similar lenses remain undetected within its first three years of observations. All COWLS data is publicly available on GitHub.