Quasar lenses and galactic streams: outlier selection and Gaia multiplet detection
Abstract
I describe two novel techniques originally devised to select strongly lensed quasar candidates in wide-field surveys. The first relies on outlier selection in optical and mid-infrared magnitude space; the second combines mid-infrared colour selection with Gaia spatial resolution, to identify multiplets of objects with quasar-like colours. Both methods have already been applied successfully to the Sloan Digital Sky Survey, ATLAS and Dark Energy Survey footprints: besides recovering known lenses from previous searches, they have led to new discoveries, including quadruply lensed quasars, which are rare within the rare-object class of quasar lenses. As a serendipitous by-product, at least four candidate Galactic streams in the South have been identified among foreground contaminants. There is considerable scope for tailoring the WISE-Gaia multiplet search to stellar-like objects, instead of quasar-like, and to automatically detect Galactic streams.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- October 2017
- DOI:
- 10.1093/mnras/stx1650
- arXiv:
- arXiv:1705.08900
- Bibcode:
- 2017MNRAS.471.2013A
- Keywords:
-
- gravitational lensing: strong;
- methods: statistical;
- surveys;
- Galaxy: structure;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- MNRAS subm. 21/04, revised version after referee report. 10 pages, 5 figures