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Researchers working with early Euclid space telescope images report 72 additional galaxy–galaxy strong lens candidates in the mission’s Quick Release 1 data. Strong lensing happens when a massive foreground galaxy bends light from a background galaxy and creates arcs, rings, or multiple images. The new set includes 38 “grade A” confident candidates and 34 “grade B” probable ones. The team also shows that an earlier selection step had unintentionally excluded a class of bright, low‑redshift lenses, so these objects had been missed before.
The candidates come from a search of 63.1 square degrees of Euclid imaging. The team used two independent approaches. One combined machine‑learning models with expert visual checks. The other was a purely human visual search aimed at objects the machine step had excluded. The earlier exclusion involved objects listed in the Gaia catalogue, and it led to missing more than 10% extra lens candidates compared to the first SLDE catalogue.
The paper reports that detailed, semi‑automated lens modelling—fitting simple mass models to the images—confirms at least 41 of the 72 systems so far. That confirmation rate is similar to what the authors found in an earlier SLDE study (315 confirmed out of 488 candidates). The new sample contains some interesting configurations: several edge‑on disc galaxy lenses, sources with arcs close to the lens centre, “red” background sources, and one case where an edge‑on disk lenses a galaxy merger to produce both an Einstein ring (a near‑complete ring of light formed when alignment is close) and a separate doubly imaged feature.
The data come from Euclid’s VISible instrument (VIS), which images optical light from about 550 to 900 nanometres with 0.1 arcsecond pixels, and the Near‑Infrared Spectrometer and Photometer (NISP), which covers roughly 950–2020 nanometres. For each candidate the team extracted 10×10 arcsecond image cutouts. Because wide surveys produce large files, the group commonly used compressed JPEG versions of the images and several visualization styles to help inspectors spot lensing patterns.
Why this matters: Euclid is expected to find very large numbers of galaxy–galaxy strong lenses across the sky. Adding these bright, nearby systems increases the projected count of high‑confidence lenses in the full Euclid Wide Survey to about 120,000. Strong lenses are valuable tools. They let astronomers measure the total mass in galaxies (including dark matter), test cosmological parameters such as the Hubble constant, and magnify very distant galaxies so we can study them in more detail. Important caveats remain. The newly found candidates are not all yet model‑confirmed, and the paper shows that selection choices—like excluding certain catalogue entries—can bias which lenses are found. That means systematic searches must combine automated methods and careful visual checks to avoid missing particular kinds of lenses.