Lunch talk on Sep. 7, 2026

Redshift-resolved lensing geometry in a single JWST cluster field

Speaker: Lin Nie (SHAO)

Venue: SWIFAR Building 2111

Time: 12:45 PM, Monday, Sep. 7, 2026

Abstract: 

The geometric information in weak gravitational lensing has traditionally been extracted primarily through ensemble statistics over large populations of lenses and sources. Here we show that JWST shifts weak-lensing geometry from an ensemble-level statistic to a measurement within an individual gravitational system. Using JWST/NIRCam imaging of SMACS J0723.3−7327 together with HST+JWST photometric redshifts calibrated redshifts, we measure the shear ratio between source populations at different redshifts within the same cluster annulus. Over 1.3 ≲ zcut ≲ 3.0, the measured scaling is consistent with the lensing-efficiency prediction of flat ΛCDM, reaching approximately 13% fractional precision on the amplitude from a single cluster.