In a paper appearing in The Astrophysical Journal, a team led by Daniel Stern uses machine learning algorithms to pour through sky survey images looking for distant quasars whose light has been affected by the gravity of intervening galaxies. If the distant quasar and intervening galaxy are aligned just right, gravity can act like a funhouse mirror, creating multiple, distorted images of that background galaxy. 

This publication quadrupled the number of known systems where one quasar’s light is distorted into four separate objects. These four-times seen quasars can be used to study the expansion of the universe and other problems concerning the geometry of space and time. While this paper focuses on the discovery of these objects, we look forward to seeing all the additional results that come from just finding these systems.

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Caltech press release

“Gaia GraL: Gaia DR2 Gravitational Lens Systems. VI. Spectroscopic Confirmation and Modeling of Quadruply-Imaged Lensed Quasars,” D. Stern et al., to be published in The Astrophysical Journal (preprint on arxiv.org)