The COSMOS-Web Lens Survey (COWLS) I: discovery of >100 high redshift strong lenses in contiguous JWST imaging

Abstract

We present the COSMOS-Web Lens Survey (COWLS), a sample of over 100 strong lens candidates from the 0.54deg2 COSMOS-Web survey, discovered using exquisite James Webb Space Telescope (JWST) imaging across four wavebands. Following two rounds of visual inspection, over 100 candidates were ranked as ‘high confidence’ or ‘likely’ by at least 50 percent of inspectors. The COWLS sample has several notable properties: (i) magnified source galaxies spanning redshifts z ∼ 0.1 to z ∼ 9, which therefore extend into the epoch of reionization; (ii) the highest-redshift lens galaxies known, pushing galaxy density profile evolution studies beyond z ∼ 2; (iii) all lenses are distributed within a contiguous 0.54deg2 region, allowing for joint strong and weak lensing analyses; and (iv) a subset exhibits lensed source emission ray-traced near the lens galaxy centres, enabling studies of supermassive black holes and dust absorption. A key innovation of our approach is the use of lens modelling to aid in identifying lenses that may otherwise be missed. This paper is accompanied by the first COWLS public release, providing JWST NIRCam imaging in four bands, lens models, pixelized source reconstructions and lens redshift estimates.