Gravitational lenses are at the forefront of current research in cosmology and astrophysics. In astrophysics, they have been used to uncover the structure of massive galaxies, to study how supermassive black holes relate to their host galaxies, and to gain insight into quasar accretion disks as well as their black hole spin. In cosmology, they have contributed to measuring the distribution of dark matter around galaxies and the expansion history of the universe.
Since the discovery of the first gravitationally lensed quasar in 1979, gravitational lenses have become powerful probes of astrophysics and cosmology. Because they require a very specific configuration between a background quasar (a bright, distant object powered by a supermassive black hole) and a foreground lensing galaxy, quadruply lensed quasars are especially rare. In fact, to date there are only about three-dozen such objects known over the entire sky.
Astronomers from the United States Naval Observatory (USNO) in conjunction with colleagues from the University of California, Davis, and Rutgers University have discovered the first quadruple gravitational lens candidate within data from the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) using a combination of all-sky survey data from the USNO Robotic Astrometric Telescope (URAT) and the Wide-field Infrared Survey Explorer (WISE).
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