2007/07/18 by Issha Kayo, Naohisa Inada, Masamune Oguri +7
Physics and Astronomy · #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #Gamma-ray bursts and supernovae #astro-ph
paper · pdf · doi:10.1086/521652
published as Astron.J.134:1515-1521,2007 · 19 pages, 7 figures, AJ accepted
arxiv created 2007/07/18 · openalex publication_date 2007/08/21 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We report the discovery of a quadruply imaged quasar, SDSS J125107.57+293540.5, selected from the Sloan Digital Sky Survey. Follow-up imaging reveals that the system consists of four blue pointlike components in a typical cusp lens geometry surrounding a central red galaxy. The source redshift is 0.802, and the lens redshift is 0.410. The maximum image separation between the lensed components is 1.79''. While the image configuration is well reproduced by standard mass models with reasonable parameter values, the flux ratios predicted by these models differ from the observed ratios in all bands. This is suggestive of small-scale structure in this lens, although a definitive identification of the anomaly requires more accurate photometry and astrometry.