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

  • Guillaume Mahler
  • , James W. Nightingale
  • , Natalie B. Hogg
  • , Ghassem Gozaliasl
  • , Jacqueline McCleary
  • , Qiuhan He
  • , Edward Berman
  • , Maximilien Franco
  • , Daizhong Liu
  • , Richard J. Massey*
  • , Wilfried Mercier
  • , Diana Scognamiglio
  • , Marko Shuntov
  • , Maximilian Von Wietersheim-Kramsta
  • , Louise Paquereau
  • , Olivier Ilbert
  • , Natalie Allen
  • , Sune Toft
  • , Hollis B. Akins
  • , Caitlin M. Casey
  • Jeyhan S. Kartaltepe, Anton M. Koekemoer, Henry Joy McCracken, Jason D. Rhodes, Brant E. Robertson, Jorge A. Zavala, Nicole E. Drakos, Andreas L. Faisst, Georgios E. Magdis, Shuowen Jin
*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

The COSMOS-Web Lens Survey (COWLS) presents the first systematic search for strong gravitational lenses in the COSMOS-Web 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, multiwavelength 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 undiscovered within its first three years of observations. All COWLS data are publicly available on GitHub.

Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society: Letters
Volume544
Issue number1
Pages (from-to)L8-L14
ISSN1745-3925
DOIs
Publication statusPublished - 2025

Keywords

  • Galaxies: structure
  • Gravitational lensing: strong

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