Confirming lensed-quasar candidates with DESI and P200 spectroscopy I. 14 lensed quasars and 8 lensed galaxy (2509.03858v1)

Abstract: Lensed quasars are powerful probes of cosmology, the co-evolution of supermassive black holes and their host galaxies, and the distribution of dark matter. We cross-match 1,724 previously identified candidates from HSC, KiDS, and the DESI Legacy Imaging Surveys (DESI-LS) with DESI DR1, obtaining 937 DESI spectra for 677 unique systems. Combining DESI spectroscopy with observations from the Palomar 200-inch Double Spectrograph (P200/DBSP), we confirm three lensed quasars with source redshifts of 1.71, 1.93, and 3.23 and Einstein radii of 0.96, 0.39, and 1.07 arcsec, respectively. We further identify 11 high-confidence candidates that are well reproduced by a simple singular isothermal ellipsoid (SIE) model, exhibit lens galaxies in the image modeling, and have at least one available spectrum; across these, the Einstein radius spans 0.39 to 2.34 arcsec and the source redshift spans 1.13 to 2.88. In 8 of the 11 cases, the systems already satisfy our lensing criteria except that only one quasar image currently has a spectrum; obtaining a second spectrum for the other image would enable immediate confirmation. As by-products, we report eight new lensed galaxies spanning galaxy- to group-scale lenses. These results provide valuable targets for follow-up studies and underscore the efficiency of wide-field spectroscopic surveys such as DESI in confirming gravitationally lensed quasars and galaxies.