Abstract:
Context. Strongly lensed quasars are fundamental sources for cosmology. The Gaia space mission covers the entire sky with the
unprecedented resolution of 0.18′′ in the optical, making it an ideal instrument to search for gravitational lenses down to the limiting
magnitude of 21. Nevertheless, the previous Gaia Data Releases are known to be incomplete for small angular separations such as
those expected for most lenses.
Aims. We present the Data Processing and Analysis Consortium GravLens pipeline, which was built to analyse all Gaia detections
around quasars and to cluster them into sources, thus producing a catalogue of secondary sources around each quasar. We analysed the
resulting catalogue to produce scores that indicate source configurations that are compatible with strongly lensed quasars.
Methods. GravLens uses the DBSCAN unsupervised clustering algorithm to detect sources around quasars. The resulting catalogue
of multiplets is then analysed with several methods to identify potential gravitational lenses. We developed and applied an outlier
scoring method, a comparison between the average BP and RP spectra of the components, and we also used an extremely randomised
tree algorith...