From the March 2010 issue

How are we sure that images classified as gravitational lensing are a distortion of light, not existing objects?

Alexandros Vorrias, Chios, Greece
By | Published: March 29, 2010 | Last updated on May 18, 2023
May 2010 lensing
To verify that multiple images are one object that’s been gravitationally lensed, astronomers model the foreground lens object and the background object. The Sloan Lens ACS Survey (SLACS) survey imaged gravitational lens candidates with the Hubble Space Telescope (left panels) and compared them to computational models (right panels). The illustration shows how a massive object lenses light from a galaxy.
A. Boltan, for the SLACS team and NASA/ESA; Astronomy: Roen Kelly

To definitively conclude the lens nature of an image, we should identify the lens (a galaxy and/or a galaxy cluster) and model its mass distribution using what researchers know about galaxy and galaxy cluster physics.