Abstract
We present a new parametric lens model for the massive galaxy cluster Abell 2744 based on new ultra-deep JWST imaging taken in the framework of the UNCOVER program. These observations constitute the deepest JWST images of a lensing cluster to date, adding to existing deep Hubble Space Telescope (HST) images and the recent JWST ERS and DDT data taken for this field. The wide field-of-view of UNCOVER (∼45 arcmin2) extends beyond the cluster’s well-studied central core and reveals a spectacular wealth of prominent lensed features around two massive cluster sub-structures in the north and north-west, where no multiple images were previously known. We identify 75 new multiple images and candidates of 17 sources, 43 of which allow us, for the first time, to constrain the lensing properties and total mass distribution around these extended cluster structures using strong lensing (SL). Our model yields an effective Einstein radius of θE, main = 23.2″ ± 2.3″ for the main cluster core (for zs = 2), enclosing a mass of M( < θE, main) = (7.7 ± 1.1) × 1013 M⊙, and θE, NW = 13.1″ ± 1.3″ for the newly discovered north-western SL structure enclosing M( < θE, NW) = (2.2 ± 0.3) × 1013 M⊙. The northern clump is somewhat less massive with θE, N = 7.4″ ± 0.7″ enclosing M( < θE, N) = (0.8 ± 0.1) × 1013 M⊙. We find the northern sub-structures of Abell 2744 to broadly agree with the findings from weak lensing (WL) analyses and align with the filamentary structure found by these previous studies. Our model in particular reveals a large area of high magnification values between the various cluster structures, which will be paramount for lensed galaxy studies in the UNCOVER field. The model is made publicly available to accompany the first UNCOVER data release.
Furtak, Lukas J